Is Bromine Out Of Style And Why?

[Aric]

Ok, so several years ago when I became a spa owner, you threw a bromine floater that held little bromine tablets in it, into your spa, refilled it once a week, checked the PH once or twice a week and used an oxygenating shock once a week (and additional shock after heavy use.)

It worked well. I never had any problems or smells with this method (and I have people with sensitive skin in the family). The hardest thing was keeping the PH correct, but with the ozonator things stayed relatively stable. I found that the PH contributed more to the bromine smell and skin sensitivity then just the bromine itself.

Now people are talking about using chlorine a lot instead of bromine. Is there a reason for the change in attitude? I've been told to add a tablespoon of chlorine once a day and that's it. Hmm, I'd rather refill a floater once a week.

[Trigger]

Ok, so several years ago when I became a spa owner, you threw a bromine floater that held little bromine tablets in it, into your spa, refilled it once a week, checked the PH once or twice a week and used an oxygenating shock once a week (and additional shock after heavy use.)

It worked well. I never had any problems or smells with this method (and I have people with sensitive skin in the family). The hardest thing was keeping the PH correct, but with the ozonator things stayed relatively stable. I found that the PH contributed more to the bromine smell and skin sensitivity then just the bromine itself.

Now people are talking about using chlorine a lot instead of bromine. Is there a reason for the change in attitude? I've been told to add a tablespoon of chlorine once a day and that's it. Hmm, I'd rather refill a floater once a week.

Bromine is stil the sanitizer of choice for many spas. However, Dichlor is just as, if not more popular. Dichlor, I belive is more exact in the amount you add, and allows you to soak without the sanitzier in the water. (adding it post soak, allows the dichlor to sanitize the water, and within a few hours, the chlorine levels drop away. )

My dichlor routine calls for me to add 1 teaspoon per person after using the tub. I don't add it every day, only when I use the tub. Maybe 2-3 a week.

It's a great system/method.

I'd rather soak in low to no sanitizer spa and add chlorine as needed and based on the use of the tub, than have a floater bopping around dispensing bromine all willy-nilly.

[chem geek]

Bromine is a good system and as you point out it has less maintenance since you don't have to add sanitizer every day. Some people have sensitivity to bromine and others find it smells more (though others say that using chlorine smells more, but the smell is different). Using chlorine is less expensive, but for a spa that's not a lot of money anyway.

I really don't know if there is such a shift as you describe or why. I think that on this forum there has been discussion about how to *properly* use chlorine -- i.e. not using Dichlor exclusively but using some to get to 20 ppm CYA and then switching to bleach, but not a shift away from bromine to chlorine unless someone has specific sensitivity to bromine.

Trigger, you were writing at the same time as I was. If you use only Dichlor then you will build up CYA and after a few weeks or a month you will have far less disinfecting chlorine in your spa even right after adding more Dichlor. This makes the risk of getting hot tub itch much higher as several on this forum have found out. Also, not adding chlorine every day probably means that your Free Chlorine level is low after the 2nd day and would again allow for some hearty bacteria to grow. The safer approach would be to use Dichlor for the first week (or until you've added the equivalent of about 22 ppm FC which is around 20 ppm CYA when using Dichlor) and then switch to using bleach.

[Trigger]

Bromine is a good system and as you point out it has less maintenance since you don't have to add sanitizer every day. Some people have sensitivity to bromine and others find it smells more (though others say that using chlorine smells more, but the smell is different). Using chlorine is less expensive, but for a spa that's not a lot of money anyway.

I really don't know if there is such a shift as you describe or why. I think that on this forum there has been discussion about how to *properly* use chlorine -- i.e. not using Dichlor exclusively but using some to get to 20 ppm CYA and then switching to bleach, but not a shift away from bromine to chlorine unless someone has specific sensitivity to bromine.

Switching to bleach? To sanitize the spa? I've never heard of that. I've never experienced any bad ordor from the dichlor, as I mentioned, it's added post soaking and disapates to very low levels (1ppm or less) by the next day. ?

It's been my expereince many folks use Dichlor exclusively for their sanititation and shocking, and have done so for years. Do you have a pointer to this "discussion"? Thanks.

[chem geek]

Yes, let me find the posts on this forum or those who had hot tub itch using only Dichlor. I'll modify this post with those links...give me a few minutes. OK, here it is:

pH and Ta

Help Needed For Indoor Hot Tub Please, is chlorine safe indoors

Switching From Softsoak to Chlorine

Liquid Chlorine Question

There are other links where I describe what goes on in more detail, but the above are the ones where users of this forum report that they had hot tub itch (or thought they had it) or equivalent (hot tub lung).

The relationship between chlorine and Cyanuric Acid (CYA) is technical though it is really just equilibrium chemistry. CYA "protects" chlorine from getting broken down from sunlight as quickly. It offers this protection by combining with chlorine to form new compounds called chlorinated isocyanurates, but this is essentially just chlorine that is bound to CYA. The problem is that these Cl-CYA compounds have virtually no disinfection or sanitizing capability and almost no oxidizing capability either and though some in the industry claim otherwise, they really don't prevent algae either. Only the disinfecting form of chlorine, hypochlorous acid (HOCl), does all of these things -- disinfects and kills or inactivates bacteria, viruses and some protozoa (not effective with cysts, however) and kills or inhibits algae. Essentially, you can think of CYA as providing a chlorine "buffer" that stores chlorine and releases it as the disinfecting chlorine gets used up, but that this chlorine "in storage" isn't effective on its own. This link is to technical information I've put together and calculated regarding the chlorine/CYA relationship.

I am currently working with several companies in the industry to try and have this information disseminated, but so far they disagree with my conclusions though they do understand what I have done. This link is to my analysis of the main study they use that they claim justifies any amount of CYA. Not everyone agrees with them as this link from the Department of Health in Pennsylvania indicates. I don't agree with the Pennsylvania recommendation of not using Dichlor at all as that causes other problems with having the chlorine level TOO high. I think that a balanced and knowledgeable approach keeping the CYA at the proper amount is the way to go (not too low, not too high, just right...like porridge!).

Regarding your not smelling chlorine odor, that is because the buildup of CYA by using only Dichlor has caused the disinfecting chlorine level to be so low that it does not outgas as much. If after a fresh refill of your spa you use Dichlor for a week and then switch to bleach, you will notice some odor especially right after adding the bleach, but when the bleach mixes thoroughly with the water the odor will subside. However, when you first open up the cover you will likely notice an odor if you don't have too much CYA because there is enough disinfecting chlorine to kill hot tub itch and that amount unfortunately does outgas enough to buildup under the cover. The good news is that taking off the cover for 5 minutes before getting in helps a lot to dissipate this odor. The fact that you never smell chlorine, in other words, is not necessarily a good thing (and when I refer to smelling chlorine, I mean the "clean" smell similar to bleach, not the "bad" smell associated with monochloramine or other chlorine disinfection by-products).

Hope this helps. If you have more questions or need more info, let me know.

[Trigger]

Thanks for the info Geek. I'm still trying to go through it all.

In esscence, your claiming that you need CYA (muble muble acid) in order to stablize the chlorine so that it can last longer and sanitize the spa (kill organic matter). Did I get that right? Dichlor doen't last that long in the tub, and your belive that it's effective time is too little to properly sanitize the tub? I raise my Cl to 5ppm after soaking and have good luck.

At high temps, it's my understand bleach is even less effective than dichlor, and I've heard it's damaging to the filter media. What was the benifit of bleach again?

I think many poeople who have "hot tub itch" are really suffering from improper water balance (PH being off), or perhaps have a alergic reation to dichlor (I've heard the same that some folks react poorly to bromine). Other folks Ive found were simply soaking in too high concentrations (6pp plus), and it was just stripping the oils from the skin.

I never tested for cya, I use ozone and dichlor and shock with MPS ever 2 weeks, all in all I have good luck.

Now, just for fun, could you boil all this down in simple terms. Yes, you and I fully understand all the techno garble gook....but just for fun, assume I don't.

[chem geek]

My responses to your questions below.

In esscence, your claiming that you need CYA (muble muble acid) in order to stablize the chlorine so that it can last longer and sanitize the spa (kill organic matter). Did I get that right?

Yes, this is essentially correct, but the CYA not only increases the life of the chlorine, but it decreases its effectiveness. So there is a tradeoff that must be balanced.

Dichlor doen't last that long in the tub, and your belive that it's effective time is too little to properly sanitize the tub? I raise my Cl to 5ppm after soaking and have good luck.

Actually, using only dichlor should have the chlorine last longer especially after a few months of use due to the buildup of CYA. The fact that you see the Free Chlorine (FC) level drop from 5 ppm to 1 ppm so quickly is unusual with high CYA levels (but explained below due to your use of an ozonator). So the way to think about it is that with using only Dichlor and adding enough to get to 5 ppm FC, you have a large "reserve" of chlorine, but the "active" amount of chlorine on the front lines, so to speak, is too low. I don't think your chlorine drop is due to it getting outgassed since you have high CYA levels (due to using only dichlor).

At high temps, it's my understand bleach is even less effective than dichlor, and I've heard it's damaging to the filter media. What was the benifit of bleach again?

Unless you used ONLY bleach, then such claims are just B.S. The chlorine in dichlor and in bleach when both are in the water ARE IDENTICAL. Dichlor is simply CYA plus chlorine combined into a single compound. When in water, both are there and it doesn't matter if the chlorine source came from bleach or from Dichlor, at least as far as the chlorine is concerned. But the Dichlor adds CYA and THAT causes the chlorine to become less effective as the CYA combines with chlorine to form new compounds (that I've called Cl-CYA in this post). If you didn't use Dichlor at all and had NO CYA in your pool whatsoever, then using bleach to get to, say, 4 ppm FC would be a rather high level of disinfecting chlorine and it would degrade swimsuits faster. It *might* slowly degrade cartridge filters a little faster, but I doubt it would do anything to sand or DE (speaking more generally about pools as well as spas). My wife experiences this problem with her swimsuits where she uses an indoor pool where they use no CYA and they deteriorate every winter. When using our own pool in the summer, where I have about 20 ppm CYA in the pool, her swimsuits show absolutely no sign of wear whatsoever.

This is one of several reasons why I suggest using SOME dichlor initially to get the CYA up to around 20 ppm. Then, if you maintain an FC level of 4 ppm minimum, then the amount of disinfecting chlorine is the same as if you used 0.23 ppm FC with no CYA. If you continued to use Dichlor, then your CYA would keep building up and the disinfecting chlorine level would continue to go down. At 100 ppm CYA and 4 ppm FC, the disinfecting chlorine level is only equivalent to 0.04 ppm FC with no CYA. At 200 ppm CYA and 4 ppm FC, the disinfecting chlorine level is only equivalent to 0.02 ppm FC with no CYA. That's over a factor of 10 less than the minimum level I recommend that ensures the killing of the bacteria that causes hot tub itch.

I think many poeople who have "hot tub itch" are really suffering from improper water balance (PH being off), or perhaps have a alergic reation to dichlor (I've heard the same that some folks react poorly to bromine). Other folks Ive found were simply soaking in too high concentrations (6pp plus), and it was just stripping the oils from the skin.

Though this is, of course, possible, I believe it very unlikely that people are allergic to dichlor as it is simply CYA plus chlorine and this combination is used in virtually ALL outdoor pools even though it is usually provided as trichlor or as chlorine and CYA separately. In the water, it all ends up being the same set of chemicals. You are right that some people have a sensitivity to bromine. As for 6 ppm plus, if they were using Dichlor for months, you could be in 20 ppm and not have any problem. There simply isn't enough disinfecting chlorine to attack your skin at rates fast enough to be a problem. Now 20 ppm isn't something you'd want to drink regularly since the chlorine attached to CYA will get released as it gets used up, but just remember we're talking two separate things here: the RATE of chemical reactions which is based on the disinfecting chlorine concentration and the RESERVE AMOUNT of chlorine that is available over a longer period of time as chlorine gets consumed.

By the way, the first day you add Dichlor to get to 5 ppm, the disinfecting chlorine level is equivalent to 2.2 ppm FC with no CYA. After adding more dichlor to get from 1 ppm to 5 ppm (so adding enough for 4 ppm FC) you now have the equivalent of 1.2 ppm FC with no CYA. After the third addition of Dichlor, you have the equivalent of 0.7 ppm FC with no CYA. After the fourth addition, you have the equivalent of 0.5 ppm FC with no CYA. After the fifth addition, you have the equivalent of 0.3 ppm FC with no CYA and are about where my recommendation is (you have accumulated 19 ppm CYA). In other words, in the first 4-5 times you are in your hot tub after refilling with water, you are actually exposed to higher levels of chlorine than what I am recommending you maintain after switching to bleach.

Just because your spa has too low a disinfecting chlorine level to kill the bacteria that causes hot tub itch, that doesn't mean that you are certain to get it. It's a statistical probability sort of thing -- it just increases the likelihood, that's all.

I never tested for cya, I use ozone and dichlor and shock with MPS ever 2 weeks, all in all I have good luck.

With the ozone and the MPS shock, you breakdown most organics before chlorine gets a chance to combine with them and that is a good thing. This helps prevent forming monochloramine and getting smell from that and even more importantly it prevents even worse (carcinogenic) disinfection by-products from forming. I recommend the weekly use of MPS shock, but that's for those without an ozonator. Your ozonator provides some of that oxidation capability so using less MPS is fine.

Now I understand why you are using up your chlorine so quickly even with high CYA levels after using only Dichlor. It's the ozonator. Ozone will breakdown chlorine. What I don't know is whether it will also break down CYA or the Cl-CYA compounds, but I suspect it might since it is rather powerful and CYA is technically just another organic compound.

Also, any free-floating bacteria that causes hot tub itch is probably going to get killed by your ozonator. So the primary reason you haven't had any problems with using only Dichlor is that you also have an ozonator. None of the people who reported hot tub itch (or hot tub lung) used an ozonator and they just used Dichlor exclusively.

Ozonators have benefits, as just described, but they also consume chlorine and overall cost more. Nothing wrong with that -- it's just a tradeoff between cost and possibly convenience, similar to the purchase of an salt water chlorine generator for a pool.

[Trigger]

Wow. Thanks geek.

I gather, you're a fan of 03?

I wonder, what's your take on the N2 product and method? Has this been covered in the Chem section (I admit, I don't review that forum).

once again, I apprecaite your thoughts.

[chem geek]

I wouldn't say I'm a fan of using ozone (O3), but I'm not against it. If ozone didn't break down chlorine, then I'd say it was an excellent addition to using chlorine and would be simply a cost/convenience tradeoff. You can certainly accomplish everything that ozone does by using chlorine and MPS alone (in a spa -- in an outdoor pool MPS isn't needed, at least not as much, due to sunlight which, of course, has UV light). Unfortunately, because the ozonator breaks down chlorine, it makes the decision more difficult. I'm not really for or against it for that reason.

As for Nature2 (N2), that isn't as useful. It's not that it doesn't work, but that it can't be used alone and costs a lot so why bother. The system works by putting [EDIT] metal [END-EDIT] ions into the water. Copper ions are pretty good at preventing algae, but they also tend to make hair have a green tint. Silver ions kill bacteria, but rather slowly, and they don't kill other types of pathogens as well. So the N2 system requires the use of a chlorine residual as well, though such residual can be lower than if N2 were not used.

I'd say that if you aren't allergic to bromine, then that's an excellent option since it is relatively low maintainence though it does cost more than chlorine. If you want the lowest cost or are allergic to bromine, then using chlorine as I recommend (Dichlor initially, then switch to bleach) is an excellent option. Using Bacqua is expensive and has longer-term problems, but those are mostly mitigated by the changing of the water every few months in a spa (so the Bacqua issues are worse for pools since you don't change the water regularly). If you want the convenience of Bromine but are allergic to Bromine, then Bacqua may be a decent choice. Note, however, that some users have reported bad experiences with Bacqua while others swear by it. With bromine and chlorine, used properly, both sets of users tend to like these systems and the choice is more one of higher cost greater convenience or of allergic sensitivity.

[104 Degrees]

I wouldn't say I'm a fan of using ozone (O3), but I'm not against it. If ozone didn't break down chlorine, then I'd say it was an excellent addition to using chlorine and would be simply a cost/convenience tradeoff. You can certainly accomplish everything that ozone does by using chlorine and MPS alone (in a spa -- in an outdoor pool MPS isn't needed, at least not as much, due to sunlight which, of course, has UV light). Unfortunately, because the ozonator breaks down chlorine, it makes the decision more difficult. I'm not really for or against it for that reason.

As for Nature2 (N2), that isn't as useful. It's not that it doesn't work, but that it can't be used alone and costs a lot so why bother. The system works by putting ions into the water. Copper ions are pretty good at preventing algae, but they also tend to make hair have a green tint. Silver ions kill bacteria, but rather slowly, and they don't kill other types of pathogens as well. So the N2 system requires the use of a chlorine residual as well, though such residual can be lower than if N2 were not used.

I'd say that if you aren't allergic to bromine, then that's an excellent option since it is relatively low maintainence though it does cost more than chlorine. If you want the lowest cost or are allergic to bromine, then using chlorine as I recommend (Dichlor initially, then switch to bleach) is an excellent option. Using Bacqua is expensive and has longer-term problems, but those are mostly mitigated by the changing of the water every few months in a spa (so the Bacqua issues are worse for pools since you don't change the water regularly). If you want the convenience of Bromine but are allergic to Bromine, then Bacqua may be a decent choice. Note, however, that some users have reported bad experiences with Bacqua while others swear by it. With bromine and chlorine, used properly, both sets of users tend to like these systems and the choice is more one of higher cost greater convenience or of allergic sensitivity.

Chem geek

What type of bleach? how much do you use in a 300 gallon tub?

Thank you 104 degrees

[chem geek]

The bleach must be unscented without other additives. Clorox Regular bleach that says 6% on the label (it also says 5.7% available chlorine) is actually registered with the EPA for use in pools, though they didn't bother to do that with spas since the volume is so low. You can use other unscented bleach, but some really cheap brands may be only 3% chlorine and don't guarantee their concentration.

It takes 2.5 fluid ounces (5 tablespoons) of 6% bleach to raise the FC by 4 ppm in a 300 gallon spa. If you use a cheap brand with an unknown concentration of chlorine, then you'll have to experiment to see its effects. Since you use so little chlorine, I think just paying a little more to get the Clorox bleach is worth it.

By the way, for those who want the water to feel silkier and also to provide some additional pH buffering and algae prevention, you can use 30-50 ppm Borates which you can add from 20 Mule Team Borax. It takes about 8 ounces weight (about a half of a cup or 4 fluid onces) of Borax to get to 30 ppm in a 300 gallon spa. You also need to add about 7 ounces weight (about 2.7 fluid ounces or 5.5 tablespoons) of dry acid (sodium bisulfate) to compensate for the pH since Borax raises the pH. This has been done in pools with great success. You can read more about that in this thread. Thanks to waterbear for doing the research on this.

[104 Degrees]

The bleach must be unscented without other additives. Clorox Regular bleach that says 6% on the label (it also says 5.7% available chlorine) is actually registered with the EPA for use in pools, though they didn't bother to do that with spas since the volume is so low. You can use other unscented bleach, but some really cheap brands may be only 3% chlorine and don't guarantee their concentration.

It takes 2.5 fluid ounces (5 tablespoons) of 6% bleach to raise the FC by 4 ppm in a 300 gallon spa. If you use a cheap brand with an unknown concentration of chlorine, then you'll have to experiment to see its effects. Since you use so little chlorine, I think just paying a little more to get the Clorox bleach is worth it.

By the way, for those who want the water to feel silkier and also to provide some additional pH buffering and algae prevention, you can use 30-50 ppm Borates which you can add from 20 Mule Team Borax. It takes about 8 ounces weight (about a half of a cup or 4 fluid onces) of Borax to get to 30 ppm in a 300 gallon spa. You also need to add about 7 ounces weight (about 2.7 fluid ounces or 5.5 tablespoons) of dry acid (sodium bisulfate) to compensate for the pH since Borax raises the pH. This has been done in pools with great success. You can read more about that in this thread. Thanks to waterbear for doing the research on this.

Thank you.

[104 Degrees]

The bleach must be unscented without other additives. Clorox Regular bleach that says 6% on the label (it also says 5.7% available chlorine) is actually registered with the EPA for use in pools, though they didn't bother to do that with spas since the volume is so low. You can use other unscented bleach, but some really cheap brands may be only 3% chlorine and don't guarantee their concentration.

It takes 2.5 fluid ounces (5 tablespoons) of 6% bleach to raise the FC by 4 ppm in a 300 gallon spa. If you use a cheap brand with an unknown concentration of chlorine, then you'll have to experiment to see its effects. Since you use so little chlorine, I think just paying a little more to get the Clorox bleach is worth it.

By the way, for those who want the water to feel silkier and also to provide some additional pH buffering and algae prevention, you can use 30-50 ppm Borates which you can add from 20 Mule Team Borax. It takes about 8 ounces weight (about a half of a cup or 4 fluid onces) of Borax to get to 30 ppm in a 300 gallon spa. You also need to add about 7 ounces weight (about 2.7 fluid ounces or 5.5 tablespoons) of dry acid (sodium bisulfate) to compensate for the pH since Borax raises the pH. This has been done in pools with great success. You can read more about that in this thread. Thanks to waterbear for doing the research on this.

Chem

Will the Bleach be the same color as the dichlor on my test strip? I use Quick dip. i read the free clorine part of the strip.

104

[Roger]

Chem

Will the Bleach be the same color as the dichlor on my test strip? I use Quick dip. i read the free clorine part of the strip.

104

With 6 percent chlorine in bleach, what's the other 94 percent? And how does it affect my water. With Dichlor (97% sodium Dichloro-s-triazinetrione) I add only after use 2-3 times a week. The level is below 1 PPM when I soak and 3-5 PPM after an addition, 1 TBLS. I have checked my Cyunaric Acid level mid water life and found it to be in the exceptable range. Only at the end of my 3-4 month water life have I found it to be high hence the reason for a water change. This system has worked for me for 4 tubs over 20 years without a problem. I'm not to sure where your getting your data Chem guy? My PH drops slightly because of the acid stabilizer (CYA) but I found with Bromine I had constent PH problems. I also found that because of the 2-3 PPM of bromine in the water it smelled of chlorine. I have a buddy who uses bleach also but I do not recommend it to anyone. But hey if it works go for it. I wonder what is cheaper. I pay 20 bucks for 5 LBs. of Dichlor and it lasts for over a year. I also mix in MPS for shocking and once in a while pre soak. But find it contributes to TDS way fast.

[waterbear]

With 6 percent chlorine in bleach, what's the other 94 percent?

WATER AND A BIT OF SALT AND SOME SODIUM HYDROXIDE THAT KEEPS THE CHORINE IN THE WATER.

And how does it affect my water.

ACTUALLY, IT WILL HAVE LESS IMPACT ON IT IN TERMS OF pH AND TA THAN WILL DICHLOR

With Dichlor (97% sodium Dichloro-s-triazinetrione) I add only after use 2-3 times a week. The level is below 1 PPM when I soak and 3-5 PPM after an addition, 1 TBLS. I have checked my Cyunaric Acid level mid water life and found it to be in the exceptable range.

WHAT IS ACCEPTABLE? MANY STATE HEALTH DEPARTMENTS ARE NOW SAYING THAT THE ONLY ACCEPTABLE LEVEL OF CYA IN A HOT TUB IS 0 PPM. PLEASE POST SOME TEST RESULTS THAT WERE DONE WITH A MELAMINE PRECIPITATION TEST (standard drop based test for CYA) AND NOT DONE WITH STRIPS.

Only at the end of my 3-4 month water life have I found it to be high

ONCE AGAIN, WHAT IS HIGH?

hence the reason for a water change. This system has worked for me for 4 tubs over 20 years without a problem. I'm not to sure where your getting your data Chem guy?

ACTUALLY, I HAVE SEEN THE SAME DATA AND AM ALSO FAMILIAR WITH THE PINELLAS COUNTY STUDIES.

My PH drops slightly because of the acid stabilizer (CYA) but I found with Bromine I had constent PH problems. I also found that because of the 2-3 PPM of bromine in the water it smelled of chlorine.

IF YOU HAD 2-3 PPM BROMINE IN THE WATER IT WOULD SMELL OF BROMINE, NOT CHLORINE. THEY SMELL VERY DIFFERENT. BROMINE HAS A DEFINITE SMELL THAT MANY PEOPLE DESCRIBE AS "CHEMICAL" OR "CAUSTIC".

I have a buddy who uses bleach also but I do not recommend it to anyone. But hey if it works go for it. I wonder what is cheaper. I pay 20 bucks for 5 LBs. of Dichlor and it lasts for over a year. I also mix in MPS for shocking and once in a while pre soak. But find it contributes to TDS way fast.

MPS DOES INCREASE THE SULFATE CONTENT OF THE TDS. IT'S NOT REALLY TDS THAT IS IMPORTANT BUT SPECIFICALLY WHAT COMPONENTS OF THE TDS ARE HIGH. LIQUID CHLORINE (BLEACH) CONTRIBUTES SODIUM AND CHLORIDE IONS TO THE WATER SO IT'S IMPACT IS MINIMAL. (If sodium and chloride ions has any adverse effects then every pool and spa that used a salt water chlorine generator would have had major problems over the last 30 years of their use!)_

My comments in bold and caps.

[chem geek]

waterbear answered your questions, so I'll just add a little more. Due to the process of making bleach or chlorinating liquid (both are sodium hypochlorite), for every 1 ppm FC you get about 0.8 ppm of salt. When the chlorine breaks down or disinfects or oxidizes, it gets converted to chloride where you end up with another 0.8 ppm of salt, so the net effect is that for every 1 ppm FC you get 1.6 ppm of salt. By comparison, with Dichlor, for every 1 ppm FC you get 0.8 ppm of salt after the chlorine is used up (so using Dichlor introduces half the salt compared to bleach). And as waterbear said, there is a very small amount of sodium hydroxide (lye) as well that increases the pH slightly to help stability of the chlorine. Though the initial addition of chlorine is alkaline (makes the pH rise), the usage of chlorine is acidic (makes the pH drop) and the net effect is almost exactly neutral -- just an immeasurable rise in pH from the extra sodium hydroxide (1 ppm FC after usage has a net pH rise of only 0.002).

Even with relatively high CYA from using Dichlor exclusively and having only 1 ppm FC at times, your spa is still probably bacteriologically safe for "easy-to-kill" bacteria such as E.coli and other heterotrophic bacteria because they really are very, very easy to kill. Algae takes more chlorine to kill or keep away, but with spas that are generally covered so that there is no sunlight, this is less of an issue. The primary problem with spas is the bacteria Pseudomonas aeruginosa which causes "hot tub itch". As I said in an earlier post, it's a statistical probability, not a certainty, that by using Dichlor exclusively that you will get this bacteria. There is no such thing as spontaneous generation so if you don't introduce that bacteria into your spa then it will not appear out of thin air, but in your spa after a month or two of Dichlor, any such bacteria that gets introduced is going to have a decent chance of surviving. Finally, even if you have that bacteria already in your spa, it does not mean you will notice it since not everyone gets a reaction from this bacteria.

When I look at pool water chemistry I do not look at just data for my own pool or even a few friends. I scour every pool forum I can plus official studies of data to look for patterns. With bacteria and algae you can't say that a pool or spa that is free of it has conditions that prevent it, but you CAN say that a pool or spa that has measurable bacteria or visible algae has conditions that do NOT prevent it. Like much of science, no number of examples can prove a theory to be absolutely correct, but one clear example can prove a theory wrong (or can provide other dimensions or parameters that need to be taken into account).

One of the links I provided leads to this link that describes a Commercial Spa Study that showed that high CYA levels with insufficient chlorine are bacteriologically unsafe. Unfortunately, the study is small enough that one could also conclude that just having too low an FC level is a problem but this conclusion is inconsistent with the basic chemistry that is involved and with other studies. Though this study might conclude that a disinfecting chlorine level of 0.02 is sufficient, the actual CT (chlorine concentration times time) number for the hot tub itch bacteria (30-50 for 4-log kill compared to 0.08 for 2-log kill for most bacteria -- see this link for more info) would indicate that 0.10 is a better number to use. I do not claim that the 4 ppm FC and 20 ppm CYA recommendation I am making is ideal, but I believe it to be effective. Perhaps I am being too conservative, but if you look at the links of real spa users who used Dichlor for months and developed hot tub itch (or hot tub lung) then this would indicate that clearly the level of disinfecting chlorine in their spas was insufficient to kill this bacteria.

If you added 3 ppm FC 2.5 times per week, then this would add 32 ppm CYA per month. That's not so bad, especially for the first month. However, by the end of the third month you are close to 100 ppm CYA and the combination of 100 ppm CYA and 1 ppm FC has less than 5% of the disinfecting chlorine as my recommendation of 4 ppm FC with 20 ppm CYA. The people who reported getting hot tub itch seemed to be adding more chlorine than you have -- they added about 3-4 ppm FC per day and they used their spas every day (which is probably why they used more chlorine -- running the jets has more chlorine outgas). So they were seeing monthly increases in CYA of 65 ppm CYA or about double what you were. So maybe the "cutoff" for a sanitary spa against hot tub itch is actually closer to where your spa is at the end of 3 months which would be around 1.5 months for these users. Or maybe you were just lucky with your spa or are not sensitive to this bacteria.

If the users who had hot tub itch follow my recommendations and again get hot tub itch, then this would prove that my recommendation is either wrong or insufficient to kill this bacteria. If they do not get hot tub itch, then it does not prove me right, but simply adds more evidence to support the theory.

[chem geek]

104 Degrees,

Regarding the color on your chlorine test strips, ALL sources of chlorine will register identically on ALL chlorine tests because they all produce identical disinfecting chlorine in the water. The chlorine tests don't actually test the instantaneous disinfecting chlorine level, but rather the entire chlorine reserve which includes the chlorine attached to CYA. This is known as the Free Chlorine level.

So you don't need to get new chlorine tests, but I would suggest considering getting a good overall test kit such as the Taylor K-2006 or at least get a standalone FAS-DPD drop-based chlorine test kit. It is much more accurate than strips. Strips work well for some types of tests, such as borates or pH or salt, but aren't so great with the other tests.

[chem geek]

I'd like to add a comment to something Trigger mentioned about adding chlorine after getting out of the spa and letting the sanitizer drop to low levels while in the spa. Since the high levels of chlorine (ignoring the Dichlor CYA issue for the moment) will kill pathogens in the water, if you only use the spa by yourself then you are less likely to be introducing anything into your spa that will cause a problem right away. When you get out, any bacteria you introduce are then killed when you increase the chlorine level.

The issue is more with what happens when multiple people share a spa. In that case, the main reason for maintaining a recommended chlorine level while in the spa is so that any bacteria that are introduced are killed rather quickly and not passed from one person to another. This isn't just about skin contact either, but is mostly the (I apologize for the terms) fecal-to-oral route as that is the path for many of the pathogens found in pools and spas that are not sanitized sufficiently. The generation rate for most bacteria is from 15 minutes to an hour so that means a doubling in the size of the population. A single bacteria can reproduce to over 16 million bacteria in 6-24 hours.

So, having higher levels of disinfectant is clearly important in a commercial pool or spa environment where many people are sharing the same body of water. It is less important in residential pools and spas, but I wouldn't say that it is of no concern. The people who got hot tub itch (which is often passed from place to place via swimsuits) I am sure would like to do whatever it takes to avoid it.

[104 Degrees]

104 Degrees,

Regarding the color on your chlorine test strips, ALL sources of chlorine will register identically on ALL chlorine tests because they all produce identical disinfecting chlorine in the water. The chlorine tests don't actually test the instantaneous disinfecting chlorine level, but rather the entire chlorine reserve which includes the chlorine attached to CYA. This is known as the Free Chlorine level.

So you don't need to get new chlorine tests, but I would suggest considering getting a good overall test kit such as the Taylor K-2006 or at least get a standalone FAS-DPD drop-based chlorine test kit. It is much more accurate than strips. Strips work well for some types of tests, such as borates or pH or salt, but aren't so great with the other tests.

Thanks chem geek. this is interesting

[Atali Awa]

What about Baqua??? I haven't seen any posts related to a peroxide system.

[waterbear]

What about Baqua??? I haven't seen any posts related to a peroxide system.

Baqua is a birguanide based system. The peroxide is NOT your sanitizer, it is merely the oxidizer or 'shock'. The biguanide (or PHMB) is your santizer. Peroxide is NOT a sanitizer for pools and spas. It would have to be dosed at levels that would cause discomfort or even harm to the bathers to use it as a sanitizer. For most people the disadvantages of biguanide far outweight any advantages, which is why it is not that popular.