Bleach Is Not Working For Me. Going Back To Dichlor.

[greenworks]

Thanks for the info. As for the TF100 kit, E-mail over there since I saw on TroubleFreePool a report that their system had a problem and lost some orders (see this thread). They are usually very good about shipping right away so I suspect your order may have gotten lost so E-mail using the link in the thread.

If the chlorine test you are describing is DPD, which it sounds like it is, then not seeing any FC in the test and then having it many minutes later have a reading could be Combined Chlorine (CC). Does adding the reagent in the chlorine test to show CC also have it turn red? If not, then I may have to write to Taylor about what turning red after 5-10 minutes means.

Richard I only have the FC test I believe it is the R-0001 dpd and #1 R-OOO2 DPD #2 I am pretty sure they test for FC and not for CC once I get the rest I have been emailing Dave and meg regarding my shipment. I ahve most been concerned with them not sending the package with " protect from freezing" on it as I am sure at some point it will be in a mail truck with no heat and we went through a -35'C couple of days and as I speak we are hovering at a balmy -26'C.

[greenworks]

Well got the TF-100 kit Ph 7.2, T alk 90, Cal 210, CYA 30 ( i think crappy test), chlorine was 0 but we had been on holidays for 3 days I will dose the tub and try to keep the Chlorine up to burn anything off until it can be 2-3 ppm in 24 hrs. Everything seems to be in line...

[chem geek]

Well got the TF-100 kit Ph 7.2, T alk 90, Cal 210, CYA 30 ( i think crappy test), chlorine was 0 but we had been on holidays for 3 days I will dose the tub and try to keep the Chlorine up to burn anything off until it can be 2-3 ppm in 24 hrs. Everything seems to be in line...

Yeah, the CYA test is a turbidity test so doesn't have the "count the drops" accuracy of other tests (at least the TF100 is able to measure down to 20 ppm -- the K-2006 from Taylor only goes down to 30 though Taylor has a different test kit that goes down to 20). Taylor gives some guidelines on how to do the test here. Since you are generally keeping the CYA rather low in the spa/tub, just keeping track of Dichlor addition is probably as accurate as doing the CYA test. It's not a test you'll do very often.

Take a look at this post and consider doing a chlorine (bleach) shock of say 20 ppm FC (I think 30 ppm FC is overkill).

[David66]

Check this out: I DO now have residual chlorine!

Last week when I went to add my typical 3 to 4 ounces of bleach in the morning, I thought I smelled chlorine when I opened the cover. So, I tested, and sure enough, according to the strips, there was about 5ppm. This was very odd for me, because as some of my previous posts have attested, I too have had zero residual chlorine after just a few hours. Every time I tested a day later, there was zero, zilch ppm. I could not keep a residual AT ALL. Unlike Tinybubbles I decided to stick with chlorine. I last changed the water the day after Christmas. Did the dichlor thing for about a week, then turned my attention to trying to get the ph and alk balanced using Richard's method. Alk now is decent, but my ph does seem to like to rise on me...I've decided that I'll just have to add acid every once in awhile. At any rate, my opinion was that I wasn't going to worry about not having a residual 24 hours later. I felt that my method of adding chlorine in the morning (daily) would allow for enough sanitation to keep me safe when I go to soak in the evening. Of course, I might add a bit a few hours before an anticipated heavy usage of the tub by more than one or two persons.

Anyway, yesterday and today I had residual chlorine also. SO, why do I have some now, when this has not been my experience to date? What changed? Well, my routine has changed a little in the last 2 or 3 weeks. I now add 2 ounces of mps AFTER each soak (this is based on one or two persons). I've also upped my chlorine dose to closer to 4 ounces each morning, instead of 3. Previously, I was adding mps once a week, maybe, if that. I would add bleach after a soak. Also, because it has been darn cold lately, tub use is down a bit...I would say we've only used it once or twice a week for less than an hour (one or two persons) the last 2 or 3 weeks...pretty light use.

Regarding filtration/aeration, my cleaning cycle runs one hour twice a day. The jets run at high speed briefly (just a few minutes) then on low the rest of the time. My tub (D1 Nautilus) doesn't have separate air jets or pumps.

Just thought I'd report in...bleach seems to be working for me so far. Very clean water. Adding it in the morning means not a high ppm when I go to soak in the evening, which is fine by me. So, I'm finally getting a "routine" that seems to work. Still quite a bit of work, and I don't even attempt to test daily or every time I add bleach...just not motivated to work at it that much. If the water's clear, and I've added chlorine routinely, and the ph/alk isn't all out of whack, that's good enough for me.

David

Ok, so I'm at the 2 month point with bleach. I have decided to switch back to dichlor. I am tired of fighting the ph battle. My ph stays so high, that I am sick of adding ph down. I knew bleach had a ph of 13, but I didn't think a few ounces a day would make such a big difference. My other problem is trying to maintain a chlorine residual. I simply can not do this with bleach. When I use dichlor, it's still there the next day. I know there are alot of people here that use bleach and I'm curious why they don't report problems with high ph. Do the rest of you have any problem maintaining a chlorine residual? I'm assuming that the high temps. are effecting the bleach. Anyone have any suggestions to change my mind before I make the switch?

[watersentinel]

Check this out: I DO now have residual chlorine!

Last week when I went to add my typical 3 to 4 ounces of bleach in the morning, I thought I smelled chlorine when I opened the cover. So, I tested, and sure enough, according to the strips, there was about 5ppm. This was very odd for me, because as some of my previous posts have attested, I too have had zero residual chlorine after just a few hours. Every time I tested a day later, there was zero, zilch ppm. I could not keep a residual AT ALL. Unlike Tinybubbles I decided to stick with chlorine. I last changed the water the day after Christmas. Did the dichlor thing for about a week, then turned my attention to trying to get the ph and alk balanced using Richard's method. Alk now is decent, but my ph does seem to like to rise on me...I've decided that I'll just have to add acid every once in awhile. At any rate, my opinion was that I wasn't going to worry about not having a residual 24 hours later. I felt that my method of adding chlorine in the morning (daily) would allow for enough sanitation to keep me safe when I go to soak in the evening. Of course, I might add a bit a few hours before an anticipated heavy usage of the tub by more than one or two persons.

Anyway, yesterday and today I had residual chlorine also. SO, why do I have some now, when this has not been my experience to date? What changed? Well, my routine has changed a little in the last 2 or 3 weeks. I now add 2 ounces of mps AFTER each soak (this is based on one or two persons). I've also upped my chlorine dose to closer to 4 ounces each morning, instead of 3. Previously, I was adding mps once a week, maybe, if that. I would add bleach after a soak. Also, because it has been darn cold lately, tub use is down a bit...I would say we've only used it once or twice a week for less than an hour (one or two persons) the last 2 or 3 weeks...pretty light use.

Regarding filtration/aeration, my cleaning cycle runs one hour twice a day. The jets run at high speed briefly (just a few minutes) then on low the rest of the time. My tub (D1 Nautilus) doesn't have separate air jets or pumps.

Just thought I'd report in...bleach seems to be working for me so far. Very clean water. Adding it in the morning means not a high ppm when I go to soak in the evening, which is fine by me. So, I'm finally getting a "routine" that seems to work. Still quite a bit of work, and I don't even attempt to test daily or every time I add bleach...just not motivated to work at it that much. If the water's clear, and I've added chlorine routinely, and the ph/alk isn't all out of whack, that's good enough for me.

David

David what method are you using to test your chlorine? Are you testing total residual or free chlorine residual? You shouldn't have a chlorine smell in your spa. Don't forget there is mps in your spa that reads in your chlorine test. Bleach makes a poor sanitizer in hot tubs due to the fact that it can't last in the high temperature. Is your spa dealer recommending you run a hot tub without residual chlorine? I don't know anyone in the industry that advocates the use of bleach. Most manufacturers will void your warranty if you use bleach. It raises the ph of your water and leaves behind a nightmare of scale in your pipes and equipment. You are already adding alot to your water with 2 ounces of mps and 4 ounces of bleach each day. If you have to keep adding high levels of acid to lower your ph you are compounding the problem. High levels of total dissolved solids are no better than high levels of cyanuric acid in your spa. Both can lead to decreased sanitizer efficiency but with cya its easier to raise your free chlorine levels a little. Once your water is thick with tds there is no way for your sanitizer to move freely in your water and work the way it needs to. Both of those scenarios are better than having a hot tub without a residual of sanitizer. I have been in the business for over 20 years and I have never had a customer encounter a problem while using dichlor in their spa. Have you asked your dealer about the issue? I don't know of anyone that even suggests that their spa customers test for cya. Bottom line I think you are making your water care harder than it needs to be and jeapordizing your spa. I'm afraid that the cya issue and pseudomonas bacteria issue raised by some is a little like chicken little yelling that the sky is falling. You should be much more concerned with water with no residual sanitizer allowing algae and bacteria to mulitply. Cya or not, if you keep a proper free chlorine level in your spa you will not have a problem with the psuedomonas bacteria. I venture to say that if you never read about the issue of cya here you would be happily adding dichlor to your spa once a day with crystal clear water and no problems. No spa professional would ever allow you to use bleach in your hot tub.

[David66]

I'm using Leisure Time test strips, primarily. I have a Taylor kit and have found the Leisure Time strips to be fairly accurate. I'm mainly concerned with free chlorine and that's what I'm testing for.

I'm sure that Richard (chemgeek) would beg to differ with you on many points of your reply below. I would just like to point out a couple things, then I'll defer to people who know more about water chemistry than I do.

First, why would there NOT be a chlorine smell if there is some amount of chlorine (either dichlor or bleach) in the water? If I'm in a hot tub with 5ppm of free chlorine, I can certainly smell it on my hands and skin upon exiting. What I smelled was not strong, just a hint, and then when I tested the strips showed somewhere between 3 and 5 ppm of free chlorine. Just my observation, that's all. I prefer to NOT have that chlorine smell when I soak, and the couple times I've had guests and I've added a bit a few hours before they arrived to anticipate a higher bather load, they have commented on the chlorine smell...that's unfavorable to me. I'd rather be on the low end of the FC scale when it's time to actually soak. If the FC is at 5ppm at 2pm, and more like 0 to 3 at 8pm when we soak, what could possibly happen in 6 hours that can "hurt" me?

As far as bleach not lasting due to the hot temps, well, I'm saying that I DO have a residual now...so it must be lasting. My spa dealer gave me pretty bad advice, that's why I started reading this forum. He told me to put a tablespoon of dichlor in after using the tub, and not to worry about it at all otherwise, then shock once a week. Within 2 weeks of that advice I had terrible, icky water. Following his advice results in a total lack of residual chlorine for the vast majority of the hours in the day and the week. Why would I go back to him and ask him what to do? With what I've learned here and my current method, I at least give it a daily dose of chlorine. If it doesn't have a residual, it's only for a few hours per day until I dose it again in the morning. I also have ozone and the D1 mineral system so they should help during those few hours of low or now residual, right? The rising ph is an issue, and I'm keeping an eye on that and adding muriatic acid when necessary. If I control the ph that way, how can you say that I'll have "a nightmare of scaling in the pipes and equipment"? Is an ounce or two of acid a week to control the ph a "high amount of acid"? What are the negatives of adding acid now and then? Does it contribute to higher TDS? By the way, my alk is staying pretty constant, towards the lower end of what's recommend. And to further clarify an error in your reply below, I'm NOT adding 2 ounces of mps and 4 ounces of bleach each day. I'm adding 3 to 4 ounces of bleach (more like 3 now that I do indeed have residual), and I only add mps after a soak, which right now is once or twice a week.

I have been reading all the pros and cons in the posts of this forum of bleach vs. dichlor. I don't see how adding bleach can void my warranty if I keep an eye on the pH issue. Heck, my dealer didn't give me any advice on the pH issue...I even asked him and he said "don't worry about it". I'm more concerned about it than he is. It seems that dealers would certainly like to keep selling dichlor at $12 a bottle instead of allowing their customers to buy Clorox at the grocery store for far less. I may indeed switch back to dichlor, if as you say I'm making my spa care harder than it has to be. Even if I did switch back to dichlor, I would still make daily additions. Maybe the ph would stabilize a bit...giving me one less thing to worry about. I'm only on my second fill of water, so I'm a "newbie" at this. I'm still learning trying to absorb all the information from people on this forum who know far more than I do. If I make a mistake, it will be a temporary one, not years of bad water chemistry to "scale the pipes" or "ruin the shell". I DO know that the first fill and the first 3 months were pretty much a nightmare of trying to get clear water...never really got there. And my water source here is naturally high in pH so I have to fight that battle anyway. I do know more now than I did then, and I could maybe use dichlor again on my next fill and see what happens. My main goal is get to the point where it doesn't take much time or effort to take care of it. Right now, it's not too bad, but I guess it could always be better I have clean, crystal clear water and no-one who has used the tub has complained about a rash or itching or anything...so something must be going right.

David

David what method are you using to test your chlorine? Are you testing total residual or free chlorine residual? You shouldn't have a chlorine smell in your spa. Don't forget there is mps in your spa that reads in your chlorine test. Bleach makes a poor sanitizer in hot tubs due to the fact that it can't last in the high temperature. Is your spa dealer recommending you run a hot tub without residual chlorine? I don't know anyone in the industry that advocates the use of bleach. Most manufacturers will void your warranty if you use bleach. It raises the ph of your water and leaves behind a nightmare of scale in your pipes and equipment. You are already adding alot to your water with 2 ounces of mps and 4 ounces of bleach each day. If you have to keep adding high levels of acid to lower your ph you are compounding the problem. High levels of total dissolved solids are no better than high levels of cyanuric acid in your spa. Both can lead to decreased sanitizer efficiency but with cya its easier to raise your free chlorine levels a little. Once your water is thick with tds there is no way for your sanitizer to move freely in your water and work the way it needs to. Both of those scenarios are better than having a hot tub without a residual of sanitizer. I have been in the business for over 20 years and I have never had a customer encounter a problem while using dichlor in their spa. Have you asked your dealer about the issue? I don't know of anyone that even suggests that their spa customers test for cya. Bottom line I think you are making your water care harder than it needs to be and jeapordizing your spa. I'm afraid that the cya issue and pseudomonas bacteria issue raised by some is a little like chicken little yelling that the sky is falling. You should be much more concerned with water with no residual sanitizer allowing algae and bacteria to mulitply. Cya or not, if you keep a proper free chlorine level in your spa you will not have a problem with the psuedomonas bacteria. I venture to say that if you never read about the issue of cya here you would be happily adding dichlor to your spa once a day with crystal clear water and no problems. No spa professional would ever allow you to use bleach in your hot tub.

[watersentinel]

David you seem upset by my post and I'm sorry. I am only offering to you the same advice and care I offer my own customers. I don't know who Richard is but I'd be willing to bet the farm that he is not a spa professional. I seriously doubt he's owned his spa for long if he's advocating the use of bleach. It's too bad that you got poor advice from your dealer. That makes it even more upsetting to see you getting poor advice here. There is a learning curve to owning a spa and to give up on dichlor after such a short time probably wasn't the answer. Most new spa owners have to refill in about a month. If dichlor doesn't work for you then bromine would be a much better alternative to bleach. To answer your question, with the proper use of chlorine it would be unusual to smell anything at 5 parts per milliion. If you have 5ppm fc and 6 hours later you have 0, that's a big warning sign. Either something is using up your FC or if you are using bleach, you are seeing that it doesn't last in a spa. As far as what can happen in 6 hours to hurt you, alot. Any algae, bacteria or viruses either left in your spa or introduced into it during that period (your spa is not a sealed environment) can multiply rapidly during that time. You stated that you hadn't been able to maintain a residual and suddenly you had one. A residual of fc sometimes is not enough. It's further proof of how unstable bleach is. I'm sure there are other people on this site that will tell you that their only concern over their customers in not their profit. I'm concerned with their safety and yours. A spa is a big investment and I hope yours last for years. If you write downt he pros and cons of bleach, the only possible pro you could come up with is cost. The con list would be longer. Dichlor is not expensive enough to risk your health. There are many online sources these days that keep things even more affordable. In addition, there is bromine which many people have good luck with. Clear water is nice but it doesn't mean healthy water. I'm not asking you to subtitute my judgement for your own. I'm just offering you my experience over 2 decades. Just remember that anyone can type anything on the internet. While Richard might have good intentions, I'd want proof that he's maintained healthy water in his spa or his customer's spas and had no damage to the spa or the equipment while using bleach. There are good reasons behind parameters for alkalinity and ph in spas. There are good reasons that you are to maintain a sanitizer residual in spas at all time. Hot water is a breeding ground. All that being said I hope you are enjoying your spa. I know it can be overwhelming in the beginning. Just don't throw the baby out with the bathwater so to speak.

[tony]

David you seem upset by my post and I'm sorry. I am only offering to you the same advice and care I offer my own customers. I don't know who Richard is but I'd be willing to bet the farm that he is not a spa professional. I seriously doubt he's owned his spa for long if he's advocating the use of bleach. It's too bad that you got poor advice from your dealer. That makes it even more upsetting to see you getting poor advice here. There is a learning curve to owning a spa and to give up on dichlor after such a short time probably wasn't the answer. Most new spa owners have to refill in about a month. If dichlor doesn't work for you then bromine would be a much better alternative to bleach. To answer your question, with the proper use of chlorine it would be unusual to smell anything at 5 parts per milliion. If you have 5ppm fc and 6 hours later you have 0, that's a big warning sign. Either something is using up your FC or if you are using bleach, you are seeing that it doesn't last in a spa. As far as what can happen in 6 hours to hurt you, alot. Any algae, bacteria or viruses either left in your spa or introduced into it during that period (your spa is not a sealed environment) can multiply rapidly during that time. You stated that you hadn't been able to maintain a residual and suddenly you had one. A residual of fc sometimes is not enough. It's further proof of how unstable bleach is. I'm sure there are other people on this site that will tell you that their only concern over their customers in not their profit. I'm concerned with their safety and yours. A spa is a big investment and I hope yours last for years. If you write downt he pros and cons of bleach, the only possible pro you could come up with is cost. The con list would be longer. Dichlor is not expensive enough to risk your health. There are many online sources these days that keep things even more affordable. In addition, there is bromine which many people have good luck with. Clear water is nice but it doesn't mean healthy water. I'm not asking you to subtitute my judgement for your own. I'm just offering you my experience over 2 decades. Just remember that anyone can type anything on the internet. While Richard might have good intentions, I'd want proof that he's maintained healthy water in his spa or his customer's spas and had no damage to the spa or the equipment while using bleach. There are good reasons behind parameters for alkalinity and ph in spas. There are good reasons that you are to maintain a sanitizer residual in spas at all time. Hot water is a breeding ground. All that being said I hope you are enjoying your spa. I know it can be overwhelming in the beginning. Just don't throw the baby out with the bathwater so to speak.

OK, a couple of things grabbed my attention. First, what exactly do you mean when you say bleach is unstable? Second, what damage to the spa equipment you claim that bleach will do?

[David66]

Watersentinal, I didn't intend to come across as upset with your reply. Just the nature of these forums when you can't read a person's voice inflection or facial expressions...and only have the typewritten word to go by, I guess.

Are you new to the forum? If so, welcome, and be sure to read the various discussions relating to bleach versus dichlor. There are dozens of pages, hours of reading. You'll get a lot of info regarding both methods, and if you read Richard's and Tinybubbles posts thoroughly I guarantee you'll learn something. You'll get up to speed on what people on this forum perceive to be the pros and cons of each better that way...I won't go into them here. I'm not saying which is right or wrong...the jury's still out for me. At the moment, I'm using bleach, but I can be persuaded to change my mind.

By the way, I'm not the only one here who has a hard time maintaining a residual, no matter the chlorine source. It seems maybe a more than once-a-day addition is necessary. I think the spa industry should invent a built-in automatic chlorine dosage unit. Fill the hopper up, and it dispenses a pre-determined amount of chlorine at pre-determined times. Problem solved!

David

David you seem upset by my post and I'm sorry. I am only offering to you the same advice and care I offer my own customers. I don't know who Richard is but I'd be willing to bet the farm that he is not a spa professional. I seriously doubt he's owned his spa for long if he's advocating the use of bleach. It's too bad that you got poor advice from your dealer. That makes it even more upsetting to see you getting poor advice here. There is a learning curve to owning a spa and to give up on dichlor after such a short time probably wasn't the answer. Most new spa owners have to refill in about a month. If dichlor doesn't work for you then bromine would be a much better alternative to bleach. To answer your question, with the proper use of chlorine it would be unusual to smell anything at 5 parts per milliion. If you have 5ppm fc and 6 hours later you have 0, that's a big warning sign. Either something is using up your FC or if you are using bleach, you are seeing that it doesn't last in a spa. As far as what can happen in 6 hours to hurt you, alot. Any algae, bacteria or viruses either left in your spa or introduced into it during that period (your spa is not a sealed environment) can multiply rapidly during that time. You stated that you hadn't been able to maintain a residual and suddenly you had one. A residual of fc sometimes is not enough. It's further proof of how unstable bleach is. I'm sure there are other people on this site that will tell you that their only concern over their customers in not their profit. I'm concerned with their safety and yours. A spa is a big investment and I hope yours last for years. If you write downt he pros and cons of bleach, the only possible pro you could come up with is cost. The con list would be longer. Dichlor is not expensive enough to risk your health. There are many online sources these days that keep things even more affordable. In addition, there is bromine which many people have good luck with. Clear water is nice but it doesn't mean healthy water. I'm not asking you to subtitute my judgement for your own. I'm just offering you my experience over 2 decades. Just remember that anyone can type anything on the internet. While Richard might have good intentions, I'd want proof that he's maintained healthy water in his spa or his customer's spas and had no damage to the spa or the equipment while using bleach. There are good reasons behind parameters for alkalinity and ph in spas. There are good reasons that you are to maintain a sanitizer residual in spas at all time. Hot water is a breeding ground. All that being said I hope you are enjoying your spa. I know it can be overwhelming in the beginning. Just don't throw the baby out with the bathwater so to speak.

[watersentinel]

David you seem upset by my post and I'm sorry. I am only offering to you the same advice and care I offer my own customers. I don't know who Richard is but I'd be willing to bet the farm that he is not a spa professional. I seriously doubt he's owned his spa for long if he's advocating the use of bleach. It's too bad that you got poor advice from your dealer. That makes it even more upsetting to see you getting poor advice here. There is a learning curve to owning a spa and to give up on dichlor after such a short time probably wasn't the answer. Most new spa owners have to refill in about a month. If dichlor doesn't work for you then bromine would be a much better alternative to bleach. To answer your question, with the proper use of chlorine it would be unusual to smell anything at 5 parts per milliion. If you have 5ppm fc and 6 hours later you have 0, that's a big warning sign. Either something is using up your FC or if you are using bleach, you are seeing that it doesn't last in a spa. As far as what can happen in 6 hours to hurt you, alot. Any algae, bacteria or viruses either left in your spa or introduced into it during that period (your spa is not a sealed environment) can multiply rapidly during that time. You stated that you hadn't been able to maintain a residual and suddenly you had one. A residual of fc sometimes is not enough. It's further proof of how unstable bleach is. I'm sure there are other people on this site that will tell you that their only concern over their customers in not their profit. I'm concerned with their safety and yours. A spa is a big investment and I hope yours last for years. If you write downt he pros and cons of bleach, the only possible pro you could come up with is cost. The con list would be longer. Dichlor is not expensive enough to risk your health. There are many online sources these days that keep things even more affordable. In addition, there is bromine which many people have good luck with. Clear water is nice but it doesn't mean healthy water. I'm not asking you to subtitute my judgement for your own. I'm just offering you my experience over 2 decades. Just remember that anyone can type anything on the internet. While Richard might have good intentions, I'd want proof that he's maintained healthy water in his spa or his customer's spas and had no damage to the spa or the equipment while using bleach. There are good reasons behind parameters for alkalinity and ph in spas. There are good reasons that you are to maintain a sanitizer residual in spas at all time. Hot water is a breeding ground. All that being said I hope you are enjoying your spa. I know it can be overwhelming in the beginning. Just don't throw the baby out with the bathwater so to speak.

OK, a couple of things grabbed my attention. First, what exactly do you mean when you say bleach is unstable? Second, what damage to the spa equipment you claim that bleach will do?

There are two types of chlorine. It is a misconception that all chlorine is the same. There is unstable/inorganic chlorine an example of which is sodium hypochlorite or bleach. The second type is stable/organic chlorine, an example of which is what's commonly called dichlor. With the use of sodium hypochlorite (bleach) it's incredibly difficult to maintain a proper ph. With the high ph associated with it's use there is scale buildup that clogs jets, pipe, pumps and heaters. Most people don't want the hassle of constantly monitoring and adjusting their ph which is time consumine and adds to the tds in their spa. Over time they tend to let things go and just accept the higher ph or let the time between adjustments increase.

[watersentinel]

Watersentinal, I didn't intend to come across as upset with your reply. Just the nature of these forums when you can't read a person's voice inflection or facial expressions...and only have the typewritten word to go by, I guess.

Are you new to the forum? If so, welcome, and be sure to read the various discussions relating to bleach versus dichlor. There are dozens of pages, hours of reading. You'll get a lot of info regarding both methods, and if you read Richard's and Tinybubbles posts thoroughly I guarantee you'll learn something. You'll get up to speed on what people on this forum perceive to be the pros and cons of each better that way...I won't go into them here. I'm not saying which is right or wrong...the jury's still out for me. At the moment, I'm using bleach, but I can be persuaded to change my mind.

By the way, I'm not the only one here who has a hard time maintaining a residual, no matter the chlorine source. It seems maybe a more than once-a-day addition is necessary. I think the spa industry should invent a built-in automatic chlorine dosage unit. Fill the hopper up, and it dispenses a pre-determined amount of chlorine at pre-determined times. Problem solved!

David you seem upset by my post and I'm sorry. I am only offering to you the same advice and care I offer my own customers. I don't know who Richard is but I'd be willing to bet the farm that he is not a spa professional. I seriously doubt he's owned his spa for long if he's advocating the use of bleach. It's too bad that you got poor advice from your dealer. That makes it even more upsetting to see you getting poor advice here. There is a learning curve to owning a spa and to give up on dichlor after such a short time probably wasn't the answer. Most new spa owners have to refill in about a month. If dichlor doesn't work for you then bromine would be a much better alternative to bleach. To answer your question, with the proper use of chlorine it would be unusual to smell anything at 5 parts per milliion. If you have 5ppm fc and 6 hours later you have 0, that's a big warning sign. Either something is using up your FC or if you are using bleach, you are seeing that it doesn't last in a spa. As far as what can happen in 6 hours to hurt you, alot. Any algae, bacteria or viruses either left in your spa or introduced into it during that period (your spa is not a sealed environment) can multiply rapidly during that time. You stated that you hadn't been able to maintain a residual and suddenly you had one. A residual of fc sometimes is not enough. It's further proof of how unstable bleach is. I'm sure there are other people on this site that will tell you that their only concern over their customers in not their profit. I'm concerned with their safety and yours. A spa is a big investment and I hope yours last for years. If you write downt he pros and cons of bleach, the only possible pro you could come up with is cost. The con list would be longer. Dichlor is not expensive enough to risk your health. There are many online sources these days that keep things even more affordable. In addition, there is bromine which many people have good luck with. Clear water is nice but it doesn't mean healthy water. I'm not asking you to subtitute my judgement for your own. I'm just offering you my experience over 2 decades. Just remember that anyone can type anything on the internet. While Richard might have good intentions, I'd want proof that he's maintained healthy water in his spa or his customer's spas and had no damage to the spa or the equipment while using bleach. There are good reasons behind parameters for alkalinity and ph in spas. There are good reasons that you are to maintain a sanitizer residual in spas at all time. Hot water is a breeding ground. All that being said I hope you are enjoying your spa. I know it can be overwhelming in the beginning. Just don't throw the baby out with the bathwater so to speak.

David

David thanks for the warm welcome. I had a customer call me out because of their water problems and showed me where they were getting their advice to use bleach. So here I am.

[chem geek]

watersentinal,

Please read this post/thread and understand that what is advocated regarding bleach is NOT to use only bleach, but to use Dichlor initially to build up the CYA level to at least 20 ppm (about one week's worth of Dichlor for daily spa use and addition) and probably not more than 50 ppm and then switching to unscented bleach (or chlorinating liquid or lithium hypochlorite). There are pros and cons with each approach: Dichlor-only vs. Dichlor then bleach. I only know the chemistry of what goes on plus users experience on these forums and it is consistent with most of what people have been seeing, both in pools and in spas. However, since it sounds like you only want to hear from those who either have spas or work with people who do, I'll let waterbear and others comment with experience.

One thing that we've figured out on this forum is that most people use too little oxidizer (chlorine or MPS) regardless of their source of chlorine. We've calculated rough rules of thumb based on person-hour soak time, but adjustment with testing is needed. The only reason I even got interested in the spa forum (I have a pool and came from pool forums) was that there were multiple reports of hot tub itch or hot tub lung (some diagnosed by doctors) and these all occurred after 2 or more months of Dichlor-only usage. This doesn't prove anything and in fact the CT (chlorine concentration times time) values in the literature are inconsistent regarding Pseudomonas aeruginosa (the bacteria that causes hot tub itch).

There were also multiple reports of people using Dichlor only where their water was harder to maintain after a month or so of usage. This could just be the problem of not using enough chlorine, but it could also be that the buildup of CYA slows down the breakdown of monochloramine too much. We haven't had enough experience with users on this forum to know this one way or the other yet.

I have said in other posts that most bacteria are very easy to kill and most people have found no problems with the Vermont/Northman method of adding Dichlor after one gets out of their spa. But to say that the chemistry of chlorine in terms of its disinfection and oxidation capability doesn't decline significantly with higher CYA levels from continued Dichlor usage would be incorrect and the primary motivation to using Dichlor then bleach is to provide more consistent disinfection and oxidation capability (rate, not capacity). You can read more about the pH issues in the thread I linked to above plus this thread and others. It is incorrect to only look at the pH of the source of chlorine without accounting for the acidity of the usage of chlorine itself (hypochlorous acid --> chloride ion). The solution to rising pH (from outgassing of carbon dioxide) is counter-intuitive (lowering the TA) and works for some people's spas/tubs while those with significantly higher aeration in their spas have a harder time maintaining pH and would have to either add acid more frequently or punt and use Dichlor only.

Hillbilly Hot Tub astutely points out in some posts on this thread that it's just simpler to advice using Dichlor only since that's simpler and provides a source of net acidity (from chlorine usage) to counter the outgassing of carbon dioxide from aeration. If you have a customer that isn't going to monitor their pH nor try and lower the TA or reduce aeration (amount of air in jets) to see if they can reduce the rate of rise or otherwise can't keep their pH lower (because they don't want to use acid), then they shouldn't use Dichlor then bleach.

Richard

[chem geek]

By the way, I'm not the only one here who has a hard time maintaining a residual, no matter the chlorine source. It seems maybe a more than once-a-day addition is necessary. I think the spa industry should invent a built-in automatic chlorine dosage unit. Fill the hopper up, and it dispenses a pre-determined amount of chlorine at pre-determined times. Problem solved!

David

David,

What you describe is the primary reason many people use bromine instead of chlorine since slow-dissolving bromine tablets give you at least some continual addition of disinfectant/oxidizer. Regular shocking (with MPS or chlorine) replenishes the bromine. Also, the bromine combined with ammonia/urea from sweat (bromamine) is still a disinfectant and smells different than chloramine (some like it more; others less).

The pool industry does have an automatic chlorine dispensing system in The Liquidator, but that's not designed for spas though it wouldn't be hard for someone to scale it down with appropriate dosing rates. Peristaltic pumps are another option. Of course, the most common automated chlorine system in residential pools are saltwater chlorine generator (SWG) systems.

Richard

[David66]

Hi Richard,

Yes, I did look at the dispenser solutions that are out there. Nothing that works for a spa very well yet...

By the way did you notice my other post regarding the fact that I am realizing some residual chlorine now? This is surprising news to me...I had pretty much given up on the idea. If you recall some of our earlier exchanges, I was bemoaning the fact that I would never have any measurable chlorine after, say 10 hours or so. Recently I am noticing residual, up to 5ppm some 24 hours after my dosing. I've actually cut back on the amount of bleach I put in, from 4 to 3 ounces. I would be curious as to what you think might be the reason? If you read my post from yesterday in this thread, you'll get the background, and my suspicion of why I now have some...

Regards,

David

By the way, I'm not the only one here who has a hard time maintaining a residual, no matter the chlorine source. It seems maybe a more than once-a-day addition is necessary. I think the spa industry should invent a built-in automatic chlorine dosage unit. Fill the hopper up, and it dispenses a pre-determined amount of chlorine at pre-determined times. Problem solved!

David

David,

What you describe is the primary reason many people use bromine instead of chlorine since slow-dissolving bromine tablets give you at least some continual addition of disinfectant/oxidizer. Regular shocking (with MPS or chlorine) replenishes the bromine. Also, the bromine combined with ammonia/urea from sweat (bromamine) is still a disinfectant and smells different than chloramine (some like it more; others less).

The pool industry does have an automatic chlorine dispensing system in The Liquidator, but that's not designed for spas though it wouldn't be hard for someone to scale it down with appropriate dosing rates. Peristaltic pumps are another option. Of course, the most common automated chlorine system in residential pools are saltwater chlorine generator (SWG) systems.

Richard

[lmartine]

David66, my experience is similar to yours, no chlorine residual unti I started daily use of MPS.

My first fill was dichlor only (and lithium), and lots of it, but it still went south. My second fill was dichlor initially and then bleach, and that was dicey until I started with MPS.

As for some of the other comments in this thread, I really don't know what to think about spa 'professionals' and all of their decades of experience. Each dealer has a different approach to chemicals (one dealer swears by trichlor tablets in a bromine dispenser!) but none of their approaches worked for me.

[David66]

It does seem as though my residual appeared only after I started to regularly use MPS. By regularly, I mean after each soak, once or twice a week lately. Before I started doing that, I would use it only every once in awhile, as a shock, maybe twice a month.

Now I'm at the point where I'm trying to deduce if I'm adding the proper amount. You say you add it daily. What time of day, and how much MPS do you add each time? Are you also dosing with chlorine? If so, when do you do that and how much? Finally, what brand of MPS do you use, and how many gallons is your tub?

Lots of questions, I know. It does help to "compare notes".

FYI, I typically add 2 ounces of MPS after a soak. It is ProTeam Shock. I add 3 to 4 ounces of Clorox Bleach each morning before work, at about 7:30 am...later on weekends. The filtration cycle is usually on when I add it, jets on low speed. Once a week I add Leisure Time Defender and Enzyme. I've also been trying to keep the pH down with an ounce or two of Muriatic Acid when I see the pH get to the upper 7s. That's my "system" right now. Seems to be working (as far as I can tell...water is clear).

Thanks!

David

David66, my experience is similar to yours, no chlorine residual unti I started daily use of MPS.

My first fill was dichlor only (and lithium), and lots of it, but it still went south. My second fill was dichlor initially and then bleach, and that was dicey until I started with MPS.

As for some of the other comments in this thread, I really don't know what to think about spa 'professionals' and all of their decades of experience. Each dealer has a different approach to chemicals (one dealer swears by trichlor tablets in a bromine dispenser!) but none of their approaches worked for me.

[watersentinel]

Richard I certainly don't mean to insult you but it makes more sense to listen to spa owners and professionals. If you are sick you go to a doctor if you need legal help you go to a lawyer. It doesn't matter what a textbook says it matters how it translates to spa care. I read posts where it was suggested people lower the alkalinity in their spas to try and compensate for the ph rise from adding bleach. Metals are more soluable at lower alkalinities and that is not good for a spa. It's better advice to prevent the ph rise in the first place by not using bleach. There is just no logical reason to suggest that people use bleach. People are working too hard to try and make it work. We work hard to make spa care as easy as possible for our customers. Reading lmartine's post and others shows me that they aren't getting the help they need from their dealers. Spa and chemical dealers should be more available to their customers and more hands on. I wonder if people might be afraid to call or visit them alot worrying that they might be bothering them. It's not unusual at all for people to have problems with their first fill. Practice makes perfect. Mps is a powerful oxidizer and is very useful in the spa. I think David mentioned adding it after he soaks. Another option is to add it before you soak. It's possible to sit in a spa and by the end of the soak start to smell a little something. With mps in the water this won't happen. It's possible however to keep spa water clear and healthy with daily additions of dichlor and mps only once a week. I'm curious if the people that have to use mps to get a residual are not keeping their fc residuals high enough. If it gets low at any time algae and bacteria can be growing in the water that will use up your chlorine the next time you add it. One day you open your spa to cloudy water. It didn't just get cloudy overnight. It's been building up for some time. You just didn't realize it because you've assumed that clear water is healthy water. It's impotant to remember that if you don't keep your ph in the proper range the sanitizer can't do it's job. To be concerned about cya but have high ph levels is senseless. At the high ph levels caused by sodium hypochlorite your sanitizer is useless. While your ph is creeping up your sanitizer isn't working as effectively. When it gets bad enough you lower the ph but a cycle has started. Your water shouldn't be on a rollercoaster it should be consistent so that bacteria and algae can never get a foothold. I've read that many people are very concerned with keeping their fc residual as low as possible. I think this is something perpetuated by people marketing alternative products like mineral cartridges. Remember you are dealing with parts per million. 5 parts per million of chlorine is very very low.

[chem geek]

Richard I certainly don't mean to insult you but it makes more sense to listen to spa owners and professionals. If you are sick you go to a doctor if you need legal help you go to a lawyer. It doesn't matter what a textbook says it matters how it translates to spa care. I read posts where it was suggested people lower the alkalinity in their spas to try and compensate for the ph rise from adding bleach. Metals are more soluable at lower alkalinities and that is not good for a spa. It's better advice to prevent the ph rise in the first place by not using bleach. There is just no logical reason to suggest that people use bleach. People are working too hard to try and make it work. We work hard to make spa care as easy as possible for our customers. Reading lmartine's post and others shows me that they aren't getting the help they need from their dealers. Spa and chemical dealers should be more available to their customers and more hands on. I wonder if people might be afraid to call or visit them alot worrying that they might be bothering them. It's not unusual at all for people to have problems with their first fill. Practice makes perfect. Mps is a powerful oxidizer and is very useful in the spa. I think David mentioned adding it after he soaks. Another option is to add it before you soak. It's possible to sit in a spa and by the end of the soak start to smell a little something. With mps in the water this won't happen. It's possible however to keep spa water clear and healthy with daily additions of dichlor and mps only once a week. I'm curious if the people that have to use mps to get a residual are not keeping their fc residuals high enough. If it gets low at any time algae and bacteria can be growing in the water that will use up your chlorine the next time you add it. One day you open your spa to cloudy water. It didn't just get cloudy overnight. It's been building up for some time. You just didn't realize it because you've assumed that clear water is healthy water. It's impotant to remember that if you don't keep your ph in the proper range the sanitizer can't do it's job. To be concerned about cya but have high ph levels is senseless. At the high ph levels caused by sodium hypochlorite your sanitizer is useless. While your ph is creeping up your sanitizer isn't working as effectively. When it gets bad enough you lower the ph but a cycle has started. Your water shouldn't be on a rollercoaster it should be consistent so that bacteria and algae can never get a foothold. I've read that many people are very concerned with keeping their fc residual as low as possible. I think this is something perpetuated by people marketing alternative products like mineral cartridges. Remember you are dealing with parts per million. 5 parts per million of chlorine is very very low.

If you are talking about metal corrosion, then low pH is the primary factor that causes such corrosion, not lower alkalinity. Only if the alkalinity gets really low is there the issue that small additions of chemicals lead to large pH swings and if that's acidic so the pH gets below 7.0 over an extended period of time, then that is not good. However, the lower TA levels we are talking about to reduce carbon dioxide outgassing are around 60 ppm which is still a substantial buffer capacity for pH.

The problem with using MPS before the soak is that some people have skin sensitivity to it. Otherwise, it's a great oxidizer and will break down ammonia/urea from sweat without forming monochloramine which smells. So for those that can use it, then it's good, but not everyone can. Unfortunately, it seems to interfere with the chlorine tests even when using the MPS interference remover.

You hit the nail on the head when you say that those not able to maintain a residual are not keeping their FC residuals high enough. Generally speaking, if one smells monochloramine, then one isn't using enough chlorine, but it's not quite as simple as that. From what we've figured out so far, it seems that the amount of ammonia/urea from sweat is around 7 ppm FC in 350 gallons for one person-hour. That's a large amount of material to oxidize. So if two people soak for a half hour, then clearly if they can use MPS then that's an option, but if they can't, then it's not clear what they can do. One user had 9 ppm FC in 40 ppm CYA and had the best soak of their life with no smell so at some level of chlorine the sweat may get oxidized about as fast as it gets released. This isn't practical once you've got more people in the tub -- the needed chlorine levels start getting pretty high. Also, if one used Dichlor-only, then after the first weeks, the disinfecting chlorine level is lower so oxidation of ammonia/urea takes longer and I don't think you can stay caught up. That would explain why most people used Dichlor after the soak instead of before to avoid the smell of monochloramine (chlorine combined with ammonia).

As for the pH effect on sanitizer, this is another area where the traditional industry knowledge isn't complete. Take a look at this post where you will see the traditional chlorine graph vs. pH. This is only an accurate graph when no CYA is present in the water. I then show what actually happens when there is CYA and you can see that the hypochlorous acid (actual disinfecting/oxidizing chlorine) is greatly reduced, but also is far less dependent on pH (this is more readily seen in the "log" graphs). The reason is that CYA acts as a hypochlorous acid buffer and resists changes in its concentration due to changes in pH. For example, with no CYA and an FC of 4 ppm, at a pH of 7.0 the hypochlorous acid concentration is 3.0 ppm, at a pH of 7.5 it's 1.9 ppm, at a pH of 8.0 it's 0.9 ppm (so, a factor of 2.1 difference between pH 7.5 and 8.0). However, with 20 ppm CYA, at a pH of 7.0 it's 0.13 ppm, at a pH of 7.5 it's 0.097 ppm, at a pH of 8.0 it's 0.082 ppm so you can see how pH affects the disinfecting chlorine level a lot less when CYA is present (so, a factor of 1.2 difference between pH 7.5 and 8.0).

I totally agree with you about there being too much fear about the chlorine level in the water, especially when there is CYA in the water. However, from what I gathered reading posts on this forum long before bleach was discussed was that the primary reason people didn't want a chlorine level during soaking is that it would then smell during soaking. If one uses Dichlor only, then except for the first week or two, the disinfecting chlorine level may get so low that it cannot keep up with oxidizing sweat, so it smells of monochloramine. So for those who cannot use MPS during a soak due to skin sensitivity, I don't know what to suggest other than what they are doing today which is minimal chlorine during the soak and dosing with chlorine after the soak.

Richard

[chem geek]

Hi Richard,

Yes, I did look at the dispenser solutions that are out there. Nothing that works for a spa very well yet...

By the way did you notice my other post regarding the fact that I am realizing some residual chlorine now? This is surprising news to me...I had pretty much given up on the idea. If you recall some of our earlier exchanges, I was bemoaning the fact that I would never have any measurable chlorine after, say 10 hours or so. Recently I am noticing residual, up to 5ppm some 24 hours after my dosing. I've actually cut back on the amount of bleach I put in, from 4 to 3 ounces. I would be curious as to what you think might be the reason? If you read my post from yesterday in this thread, you'll get the background, and my suspicion of why I now have some...

Regards,

David

David,

If you were adding 3 ounces of bleach in 350 gallons, then that might be enough to oxidize the sweat from 0.6 person-hours of soak time though this obviously varies a lot by person. MPS is an oxidizer so adding that to your routine increases the total oxidizer so you aren't running out anymore. Unfortunately, the MPS will interfere with the chlorine test, but I think what's going on is pretty straightforward. You simply weren't using enough oxidizer before. If you used more bleach you should have obtained a residual, but if you got behind and had things to oxidize in the water, then a shock of high chlorine level may have been needed to "catch up".

You said you changed your routine to add 2 ounces of MPS after each soak and that's a LOT of oxidizer. It's roughly equivalent to 12 ppm FC in 350 gallons or a little over one cup of 6% bleach! There's no wonder that makes a difference. This again just seems to point to the fact that way too little oxidizer is being used by most people in their spas. I think that for bleach since it's so "weak" in terms of low density compared to the solids of Dichlor and MPS, that people get shy on the quantities needed. If you don't keep up with the ammonia/urea from sweat, it will build up and create a large seemingly endless pit of chlorine or oxidizer demand later on.

As long as you don't have skin sensitivity to MPS, it's an alternative oxidizer to use and has the advantage of not forming smelly monochloramine the way chlorine does. It's just too bad it interferes with the chlorine test making it hard to know what the true chlorine level is -- even the interference remover didn't work well for some.

Richard

[tony]

There are two types of chlorine. It is a misconception that all chlorine is the same. There is unstable/inorganic chlorine an example of which is sodium hypochlorite or bleach. The second type is stable/organic chlorine, an example of which is what's commonly called dichlor. With the use of sodium hypochlorite (bleach) it's incredibly difficult to maintain a proper ph. With the high ph associated with it's use there is scale buildup that clogs jets, pipe, pumps and heaters. Most people don't want the hassle of constantly monitoring and adjusting their ph which is time consumine and adds to the tds in their spa. Over time they tend to let things go and just accept the higher ph or let the time between adjustments increase.

Thanks for the reply. I understand the difference between stabilized and unstabilized chlorine. It all has to do with the manufacture of the chlorine. There are only two stabilized chlorines, trichlor and dichlor, of which dichlor is OK for spa use. There are more unstabilized chlorines, but only lithium and sodium hypochlorite are suited for a spa. I wanted to be sure we weren't talking about one chlorine being more "stable" than the other. They all break down to the same sanitizing agent. I believe dichlor and lithium are preferred for spas because they are quick dissolving more than any other reason. I disagree that it is more difficult to maintain proper pH, especially compared to those using bromine who have to deal with dropping pH which, IMO, can be more destructive. Proper water balance is something that should be monitored and adjusted on an ongoing basis, no matter what.

I find that dichlor use brings my pH down and I need to add about a tablespoon of baking soda once every other week. Bleach tends to bring my pH up and I need to add about a tablespoon of dry acid every other week. In my situation, the maintenance is about the same. I am in my third month with my experiment with bleach. I am most interested in my water quality from this point to the end of four months, my usual drain and fill time. What I am looking at in particular is ease of maintenance when TDS and CYA generally start to play havoc with my water.

I will say, though, that bleach is not for new spa owners, IMO. You should have a very good working knowlege of your water chemistry and how it reacts and what it takes to correct problems such as pH swings or cloudy water. I don't advocate the use of bleach. I use it in my pool along with trichlor with excellent results and am trying it in my spa. So far all is well.

[lmartine]

David,

I have a 350g spa with an ozonator, there is low speed pump which runs continuously. I fill with hard/iron/sulfer-flavoured well water through an inline hose filter. TA is 80-100 and CYA is low (0-30 depending who tests it).

The MPS brand is 'Oxy Pro' by a company called Aquapro, evidently based here in Ottawa. No specs on the label, just say 'contains peroxysulfate'.

I started by adding 4oz 5.25% bleach and, simultaneously, just under 1 tablespoon (??ozs) of MPS with pump on high, no air and lid propped open for about 15 minutes. Chlorine goes in straight from the measuring cup and then MPS thrown on top. I do this twice a day, usually at 7ish in the morning and 6-ish at night. I have tried skipping the afternoon addition if the spa does not get used in the afternoon, but this leaves little reserve. My teenage son and 3 of his friends hopped in one evening without me adding the afternoon dose (wow, instant cesspool), but an immediate application of chlorine and MPS brought things back in line.

I really think this is still not enough chlorine though. I have been considering upping the chlorine to 8 ozs in the morning without MPS, then maybe 6 ozs in the PM and only add MPS after the last soak of the evening. Convenience (laziness) is a factor too for me so I might try two shots a day of 6ozs + 1/2 tablespoon MPS.

The ph tends to go down if no one uses the spa, then goes back up with use. I have not adjusted the pH for at least two weeks, although it has been borderline low on occasion.

FYI, I shocked yesterday with 6 full tablespoons of lithium and no MPS; 12 hours later with no bathers and there is no residual.

--

Lee

It does seem as though my residual appeared only after I started to regularly use MPS. By regularly, I mean after each soak, once or twice a week lately. Before I started doing that, I would use it only every once in awhile, as a shock, maybe twice a month.

Now I'm at the point where I'm trying to deduce if I'm adding the proper amount. You say you add it daily. What time of day, and how much MPS do you add each time? Are you also dosing with chlorine? If so, when do you do that and how much? Finally, what brand of MPS do you use, and how many gallons is your tub?

Lots of questions, I know. It does help to "compare notes".

FYI, I typically add 2 ounces of MPS after a soak. It is ProTeam Shock. I add 3 to 4 ounces of Clorox Bleach each morning before work, at about 7:30 am...later on weekends. The filtration cycle is usually on when I add it, jets on low speed. Once a week I add Leisure Time Defender and Enzyme. I've also been trying to keep the pH down with an ounce or two of Muriatic Acid when I see the pH get to the upper 7s. That's my "system" right now. Seems to be working (as far as I can tell...water is clear).

Thanks!

David

[chem geek]

I really think this is still not enough chlorine though.

:

:

FYI, I shocked yesterday with 6 full tablespoons of lithium and no MPS; 12 hours later with no bathers and there is no residual.

Lee,

It certainly does sound like a large amount of things to oxidize had built up as 6 tablespoons of Lithium Hypochlorite (assuming 35% available chlorine) in 350 gallons would be 22 ppm FC. You could try shocking again (doesn't have to be as much, unless you want to) and see if that holds longer. If it does, then this probably means you weren't using enough chlorine so were building up ammonia/urea to oxidize. I assume a FAS-DPD chlorine test was used because the DPD test (compare intensity of red color) would bleach out above 10 ppm FC making you think there was no chlorine when in fact there was a lot.

Richard

[lmartine]

Richard,

No time to shock again, I added my usual maintenance dose and somebody is already in the spa.

I still don't have a proper test kit (lost orders, lost emails, yada yada) so I can't give any proper numbers. I know the test strips are so-so, but they are in the ballpark of tests done periodically at various spa dealers.

Basically I am aiming for just the faintest hint of chlorine smell on my skin when I get out. I am currently in the 0.5-1PPM range on the test strip, which I think is too low. I need to get into the 1-2PPM range (just like it says on the spa instructions!). If I get 3-5PPM on the strip I find the chlorine smell too strong. The 10+ during shocking is obviously too much for normal usage, but is certainly not life-threating if one gets in by accident.

--

Lee

[chem geek]

TinyBubbles,

I noticed you haven't posted since February 8th. I'm guessing I offended you with my response post to yours and I'm sorry I was harsh in my response. Your experiences of bleach not sticking around relative to Dichlor are real and we never got to the bottom of why that was the case for you when for most others neither bleach nor Dichlor would stay very long until some larger oxidizer dosage was done (usually with MPS). I'm sorry.

I've been thinking more about the pH changes when using bleach because your point of the initial addition of bleach making the pH rise is completely correct even if the pH would go down later during usage (if there wasn't aeration). So even for those that have average overall pH stability or a slow pH rise using bleach, there is still a potential issue of what happens soon after the bleach is added and before it gets used up.

There is a catch-22 in that one wants a lower TA to prevent the faster tendency of the pH to rise due to outgassing of carbon dioxide, but the lower TA provides less pH buffering. When one adds bleach to raise the FC by 4 ppm, this will initially make the pH rise from 7.50 to 7.80 or from 7.70 to 8.07 if the TA is at 80 ppm. At a lower TA of 60 ppm, the pH rises from 7.50 to 7.89 or from 7.70 to 8.16. The examples starting from 7.7 would push the pH too high above 8 and would risk scaling which is the point that watersentinal was making (the exact amount of risk depends on the calcium level). So if one is adding an amount of bleach to raise the FC by 4 ppm, then one should start with a lower pH closer to 7.50 so that means adding some acid first if needed. In practice, the risk of scale may be small since the high pH may only last for an hour or so since a drop in FC will have a drop in pH, but I'd rather be conservative.

If one compares the pH changes against what happens with Dichlor, one sees that Dichlor has more risk at getting a lower pH, but is more tuned in timing once one sets a high enough TA level where the rise in pH from outgassing is close to the drop in pH from chlorine usage. The initial addition of Dichlor has a small effect on pH (it drops by about 0.04) and then the usage of chlorine has the pH continue to drop. If there were no outgassing, then a 4 ppm FC addition of Dichlor at a starting pH of 7.50 would drop to 7.29 if the TA is at 80 ppm. With outgassing, the pH will be closer to stable with the net result of a lowering in TA, in this example, from 80 to 78.6 so a slow drop in TA over time.

So what does this mean? It means that if one wants to have the same sort of rough pH stability as with Dichlor but also have outgassing help time the pH to remain stable between addition and usage of the chlorine, then one would add acid and then bleach to the spa (acid added first) and not have as low a TA. In this same example with a TA of 80, it takes 2.9 fluid ounces of 6% bleach to raise the FC by 4 ppm and would take 0.28 ounces weight (about 1.1 teaspoons) of dry acid to have the bleach addition be pH neutral. Then as the chlorine got used up, this would be acidic, but any outgassing of carbon dioxide would be alkaline and these would balance each other -- just as they do when using Dichlor. The "acid then bleach" is essentially the same as using Dichlor from a pH point of view, but without the accumulation of CYA. Just to be absolutely clear, you never add concentrated chemicals together and certainly never add acid and bleach together (that would produce chlorine gas) -- you always add these to the bulk water of the spa giving a brief time between additions for mixing (in a spa it would be very fast).

Does one have to add acid each time one adds bleach? No, but if you don't, then you need to have a lower starting pH at the time you add the bleach, such as 7.5 and not 7.7.

It is even more important for chlorine shocking that one pays attention to the pH swings. So if one were raising the FC to 10 ppm, then if using bleach one would need to either add 2-3/4 teaspoons of dry acid to be near pH neutral (and if starting at a pH of 7.5 this would drop the pH to 7.1 after the acid and then would go up to 7.5 after the bleach) or should add a smaller amount of acid to start with a pH of 7.3.

It is very, very unfortunate that there isn't a chlorine compound like Dichlor that adds chlorine with roughly no change in pH upon addition but that does not add to CYA since that would be ideal for the high-aeration environment of the hot tub. The fact is that there isn't so the compromise the spa industry has made, as HillbillyHotTub pointed out, is to use Dichlor so that at least on average the pH will usually not get too high (to avoid scaling) and to be a simple "one product" solution. The fact that CYA builds up is a side effect that is considered secondary. One caveat to this is that we still do not know if the lower disinfection rate with the higher CYA is the reason for the greater reports of hot tub itch/lung. It's not a question of whether the disinfection rate is lower, but rather whether hot tub itch bacteria is as easy to kill as most other heterotrophic bacteria which are clearly very easy-to-kill. Another caveat is whether the slower breakdown of ammonia/urea at the lower disinfecting chlorine levels in the later months is what leads to a buildup of more monochloramine in the water (unless one uses MPS).

So as has been pointed out before, using bleach is not for novice users. Dichlor is much simpler since it's pretty much just add Dichlor and once in a while add some baking soda to bring the TA back up as it slowly drops over time. Nevertheless, once in a consistent routine, it's pretty much between adding one chemical vs. two (acid and bleach).

I believe someone asked what the effect would be on TDS by using the acid and bleach vs. Dichlor. If I use the example of 4 ppm FC, then Dichlor will result in an increase in TDS of 3.6 ppm from CYA plus 3.2 ppm of salt (sodium chloride), the latter coming from the chlorine when it gets used up. For acid plus bleach, if dry acid (sodium bisulfate) is used, then this results in an increase in TDS of 5.3 ppm sulfate (actually 7.1 ppm sodium bisulfate equivalent) and 6.4 ppm salt (sodium chloride). If one uses Muriatic Acid instead, then this results in 9.9 ppm salt (sodium chloride). I am ignoring the decrease in TDS from the outgassing of carbon dioxide and it's increase when baking soda occasionally gets added. TDS by itself is not a problem. In fact, higher TDS actually makes the water less likely to scale, but it takes a lot of TDS before you see that effect. The salt content of the TDS is not a big deal. After 3 months at 4 ppm FC per day usage would result in around 900 ppm salt (if Muriatic Acid were used) or about 500 ppm sulfate plus less salt. It should be noted that MPS produces TDS of sulfate such that the same equivalent 4 ppm FC of MPS would result in a TDS of 12.3 ppm sulfate. Unfortunately, I do not know at what level high sulfates become a problem -- it's a known issue for certain materials, but I don't know if it would be an issue in spas and I suspect it isn't or else the relatively high use of MPS in spas would have had any such problems show up.

One final point regarding MPS is that this is another case of a product that is close to perfect but isn't. If some people did not get skin irritation from it (and ignoring the sulfates which could be a non-issue), then it would be great to use as a slightly acidic oxidizer (so similar to Dichlor in that sense). So for those that can tolerate MPS or can work MPS into their routine in a way that avoids irritation, then using mostly MPS lets one use less chlorine so if bleach is used that means less bleach and that means less pH swing, assuming the FC goes up and down in a narrower range. The other downside to using MPS is the havoc it seems to wreck on the chlorine measurement test, even if the interference remover is used.

Richard

[Chris W]

Personally I have two issues with MPS. The 1st being the lack of confidence in testing the sanitizer levels. The second is that the byproducts seems to give off an odor like chloramines when aeration is applied, but it seems to be much more of a chemical smell and more persistent than the chloramine smells I get with chlorine alone. If I use MPS in the tub, my wife won't use the tub very often and complains about the odor when she does. She keeps asking my why I haven't bought the spa-pilot yet. It's good to know I have her support if/when I decide to go that route. Luckily neither the wife or I seem to experience skin irriatation relate to MPS.

Chris W