Ph Readings Not Responsive To Chemicals

[D1 Spa Newbie]

Hello,

I have been a D1 Spa owner since May, 2007. The water where I live is very hard. The Ph readings have always been above the ideal range and do not seem impacted at all when I add capfuls of Ph decreaser. Unfortunately, when I add Ph decreaser to bring the Ph down, it ends up putting the Total Alkalinity (TA) level below the ideal range. Since I have been more aggressive recently trying to bring Ph down with Ph decreaser, the TA has become too low and the Ph is STILL too high and unchanged. I cannot figure it out and the dealer has not had any solutions.

I have tested the water with three different types of strips/drops and had it tested by local pool & spa stores, which have confirmed the high Ph. I am stuck now between needing to boost the TA while decreasing the Ph. What should I do?

D1 Newbie

p.s. I have been told to add Ph decreaser (1 capful) every other day until the Ph comes down. I have also been told to add Ph decreaser every two hours until the Ph comes down. Which is the right way to add Ph decreaser?

[chem geek]

What is the TA that you consider to be too low? If your spa already has a tendency for the pH to rise, you can have a lower TA, at least below 80, but probably not below 60. A lower TA should help reduce the tendency of the pH to rise. Also, try a target pH of 7.7 as the pH will rise less at lower TA and higher pH.

Also, what is your chlorine and shock regimen (how much, how often)?

Richard

[D1 Spa Newbie]

What is the TA that you consider to be too low? If your spa already has a tendency for the pH to rise, you can have a lower TA, at least below 80, but probably not below 60. A lower TA should help reduce the tendency of the pH to rise. Also, try a target pH of 7.7 as the pH will rise less at lower TA and higher pH.

Also, what is your chlorine and shock regimen (how much, how often)?

Richard

Thanks for the response, Richard. The TA tested out at 100ppm and is supposed to be 120-150 according to the guidelines for my spa. It had been 120 ppm before I added the Ph decreaser. The Ph has been 7.8 or higher for a while, regardless of the decreaser I add.

For my chlorine and shock regimen, I add 1 cap chlorine every other week and 1 cap non-chlorine shock every week. The spa has a vision cartridge (silver) and an ozone filter. I was told this would help lessen the need for sanitizers. Should I keep trying to bring the Ph down even if the TA will go lower than recommended. Should I add decreaser every other hour or every other day until it reads properly. Thanks.

[chem geek]

The TA recommendation of 120-150 is too high. It just causes more carbon dioxide to outgas faster when the jets are running and that causes the pH to rise. TA is essentially a measure of carbonation of the water. Don't add anything to increase the TA -- no Alkalinity Up -- unless it gets really low. You can certainly let the TA go down to 80, but could even let it go as low as 60 if necessary (IF your CYA level isn't too high -- since you only add one capful of Dichlor every other week, it's probably not very high). So yes, just keep adding the pH decreaser even if the TA goes lower. Let us know if the pH tends to rise less when you get the TA in the 60-80 range and when the pH is around 7.7 or so. You should find the tendency of the pH to rise to be significantly less at the lower TA level.

The Vision cartridge lets you have less sanitizer, but not zero sanitizer and with your regimen you've got zero sanitizer except for one or two days after you add chlorine every other week. Silver does kill bacteria, but does so slowly, which means while you are in the tub the bacteria and other pathogens you introduce can go to someone else and vice versa (or to yourself via fecal-to-oral route -- sort of like taking a bath). It's a risk -- better than not having the silver Vision cartridge at all, but still riskier than having chlorine added each day even if it's a lower amount. It's up to you, but I'd add at least 1 fluid ounce (if not 2) of unscented bleach after you get out each day (the next time you do a fresh refill of water, use Dichlor for the first week and then switch to bleach). That's less than normally recommended, but with the silver it might be enough to keep hot tub itch bacteria from growing and the chlorine level will be very low or near zero when you next get in so will meet your criteria of being nearly chlorine free. You'll probably also need to add the non-chlorine shock more frequently, at least once a week, though if your ozonator is working it should take care of oxidizing organics/ammonia.

Richard

[TinyBubbles]

What is the TA that you consider to be too low? If your spa already has a tendency for the pH to rise, you can have a lower TA, at least below 80, but probably not below 60. A lower TA should help reduce the tendency of the pH to rise. Also, try a target pH of 7.7 as the pH will rise less at lower TA and higher pH.

Also, what is your chlorine and shock regimen (how much, how often)?

Richard

Thanks for the response, Richard. The TA tested out at 100ppm and is supposed to be 120-150 according to the guidelines for my spa. It had been 120 ppm before I added the Ph decreaser. The Ph has been 7.8 or higher for a while, regardless of the decreaser I add.

For my chlorine and shock regimen, I add 1 cap chlorine every other week and 1 cap non-chlorine shock every week. The spa has a vision cartridge (silver) and an ozone filter. I was told this would help lessen the need for sanitizers. Should I keep trying to bring the Ph down even if the TA will go lower than recommended. Should I add decreaser every other hour or every other day until it reads properly. Thanks.

I am fascinated by your water maintenance. If you've had your tub since May and haven't had any problems with water quality, that's unreal. I know that the companies that manufacture the silver cartridges suggest low chlorine, but they usually recommend daily dosing with mps. How often do you soak and how many people usually soak? How long have you gone between water changes. Sorry to give you the 5th degree, but this is interesting.

[D1 Spa Newbie]

What is the TA that you consider to be too low? If your spa already has a tendency for the pH to rise, you can have a lower TA, at least below 80, but probably not below 60. A lower TA should help reduce the tendency of the pH to rise. Also, try a target pH of 7.7 as the pH will rise less at lower TA and higher pH.

Also, what is your chlorine and shock regimen (how much, how often)?

Richard

Thanks for the response, Richard. The TA tested out at 100ppm and is supposed to be 120-150 according to the guidelines for my spa. It had been 120 ppm before I added the Ph decreaser. The Ph has been 7.8 or higher for a while, regardless of the decreaser I add.

For my chlorine and shock regimen, I add 1 cap chlorine every other week and 1 cap non-chlorine shock every week. The spa has a vision cartridge (silver) and an ozone filter. I was told this would help lessen the need for sanitizers. Should I keep trying to bring the Ph down even if the TA will go lower than recommended. Should I add decreaser every other hour or every other day until it reads properly. Thanks.

I am fascinated by your water maintenance. If you've had your tub since May and haven't had any problems with water quality, that's unreal. I know that the companies that manufacture the silver cartridges suggest low chlorine, but they usually recommend daily dosing with mps. How often do you soak and how many people usually soak? How long have you gone between water changes. Sorry to give you the 5th degree, but this is interesting.

Now you guys have me worried and I welcome any suggestions. The tub averages 2-3 soaks a week with a maximum of 2 different users. The instructions I received from the dealer was to use chlorine every other week and shock once a week; refill every 3-4 months. Supposedly the D1 filtration system is supposed to reduce the needed chemicals. I was told the ozone filter would kill most of the bacteria. I never thought the water quality was that bad but didn't really have much to compare it too. It has had high Ph since May.

D1 Spa Newbie

[D1 Spa Newbie]

The TA recommendation of 120-150 is too high. It just causes more carbon dioxide to outgas faster when the jets are running and that causes the pH to rise. TA is essentially a measure of carbonation of the water. Don't add anything to increase the TA -- no Alkalinity Up -- unless it gets really low. You can certainly let the TA go down to 80, but could even let it go as low as 60 if necessary (IF your CYA level isn't too high -- since you only add one capful of Dichlor every other week, it's probably not very high). So yes, just keep adding the pH decreaser even if the TA goes lower. Let us know if the pH tends to rise less when you get the TA in the 60-80 range and when the pH is around 7.7 or so. You should find the tendency of the pH to rise to be significantly less at the lower TA level.

The Vision cartridge lets you have less sanitizer, but not zero sanitizer and with your regimen you've got zero sanitizer except for one or two days after you add chlorine every other week. Silver does kill bacteria, but does so slowly, which means while you are in the tub the bacteria and other pathogens you introduce can go to someone else and vice versa (or to yourself via fecal-to-oral route -- sort of like taking a bath). It's a risk -- better than not having the silver Vision cartridge at all, but still riskier than having chlorine added each day even if it's a lower amount. It's up to you, but I'd add at least 1 fluid ounce (if not 2) of unscented bleach after you get out each day (the next time you do a fresh refill of water, use Dichlor for the first week and then switch to bleach). That's less than normally recommended, but with the silver it might be enough to keep hot tub itch bacteria from growing and the chlorine level will be very low or near zero when you next get in so will meet your criteria of being nearly chlorine free. You'll probably also need to add the non-chlorine shock more frequently, at least once a week, though if your ozonator is working it should take care of oxidizing organics/ammonia.

Richard

Thanks, Richard. That is incredibly helpful. One concern is that my spa paperwork says not to use liquid chlorine or it will void the warranty. Since bleach has chlorine in it, will that pose a problem?

[D1 Spa Newbie]

What is the TA that you consider to be too low? If your spa already has a tendency for the pH to rise, you can have a lower TA, at least below 80, but probably not below 60. A lower TA should help reduce the tendency of the pH to rise. Also, try a target pH of 7.7 as the pH will rise less at lower TA and higher pH.

Also, what is your chlorine and shock regimen (how much, how often)?

Richard

Thanks for the response, Richard. The TA tested out at 100ppm and is supposed to be 120-150 according to the guidelines for my spa. It had been 120 ppm before I added the Ph decreaser. The Ph has been 7.8 or higher for a while, regardless of the decreaser I add.

For my chlorine and shock regimen, I add 1 cap chlorine every other week and 1 cap non-chlorine shock every week. The spa has a vision cartridge (silver) and an ozone filter. I was told this would help lessen the need for sanitizers. Should I keep trying to bring the Ph down even if the TA will go lower than recommended. Should I add decreaser every other hour or every other day until it reads properly. Thanks.

I am fascinated by your water maintenance. If you've had your tub since May and haven't had any problems with water quality, that's unreal. I know that the companies that manufacture the silver cartridges suggest low chlorine, but they usually recommend daily dosing with mps. How often do you soak and how many people usually soak? How long have you gone between water changes. Sorry to give you the 5th degree, but this is interesting.

I forgot to ask what temperature the spa should be set at when I am away on business. I have been leaving it at 99 degrees all winter, 24/7 and adding sanitizers in between trips.

[chem geek]

The ozonator explains why your spa hasn't turned cloudy or otherwise become unsanitary even though you haven't used very much chlorine. The silver from the Vision cartridge also keeps bacteria at bay, though slowly. So between the two, it does mean you don't need as much chlorine, but zero chlorine for extended periods of time is a little risky. Nothing to lose sleep over -- it's mostly about newly introduced pathogens and mostly about sharing them between people. The ozonator will kill anything flowing into it while the silver should take care of biofilms on surfaces so it's really just new bacteria that you shed that isn't getting killed quickly and is the main purpose of having at least some small chlorine residual.

If you decide to add chlorine regularly, yes you can use bleach though it does technically void some warranties. See this thread where I go into more detail about using bleach after initially using Dichlor.

Again, I want to emphasize that your particular situation is a low risk one because it has both a powerful oxidizer with the ozonator and a residual sanitizer of silver which inhibits bacterial growth though is not a fast-killing sanitizer. So you're certainly much better off than those that have neither and don't use chlorine frequently. Nevertheless, if you want the ultimate protection, you should use some chlorine every day so that you have at least a small residual (even 0.5 to 1 ppm Free Chlorine) when you get in. It might be easier in your case to actually use Dichlor until the CYA gets up to around 50 ppm or so and then target about 1 ppm FC when you get in as this will be a fairly low chlorine level but still much faster disinfection than what you are getting now.

Richard

[Vermonter]

Is it my imagination, or did I read somewhere in another thread that with an ozonator, it's better to go with Bromine for your sanitizer? If so, why, and how much better? The reason I ask is I'm considering switching to the bleach method at my next fill (my warranty is already null anyway, since I bought the thing used and the warranty doesn't transfer), but I'm also considering getting my ozonator fixed and/or replacing it... so which way should I go here? Stick with the Br and fix the ozonator? Go with Cl and not fix it? Or Cl and ozonator both??

Tony

[chem geek]

Tony,

We were speculating as to why there seemed to be a lot of chlorine usage for some spas that used ozonators and thought that perhaps the ozone was oxidizing the chlorine (to chlorate). However, one person recently did a test where they turned off their ozonator and saw no change in usage so we don't really know if the ozonator uses up chlorine or not. It may just be higher organic/ammonia levels in some spas (some that haven't been disinfected properly and got cloudy probably have algae growth).

Ozone can also oxidize bromine (to bromate; the sequence is bromide --> bromine --> bromate) and bromate is a suspected/possible carcinogen, but possibly in drinking water (not sure if it gets absorbed through the skin -- my guess is no). Again, we don't know if this occurs or how much. The main advantage of using an ozonator with bromine is that you want to regenerate the bromide to bromine anyway so the ozone can do that thereby reducing the need for a shock (non-chlorine MPS or chlorine).

In your case, you've got trouble keeping up the bromine level so having an ozonator might help that if the problem is bromine getting used up and converting to bromide. If instead the bromine is escaping from the spa completely (maybe outgassing), then more bromide is needed for the bromide bank, but with your use of BCDMH tablets, that just doesn't sound like the problem since they introduce more bromine (and chlorine). If I were you, I'd just fix the ozonator and stick with bromine and see if that helps keep the bromine level more stable. You can always switch to chlorine at your next refill if you wanted to and can switch back to bromine on the subsequent refill and can see which you like best (the chlorine is probably much more maintenance since you have to add it every day whereas in theory with the ozonator and bromine you only need to add some more bromide perhaps once a week at most).

Richard

[Vermonter]

Okay, thanks again Richard for the good advice.

Tony

[Vermonter]

What is the TA that you consider to be too low? If your spa already has a tendency for the pH to rise, you can have a lower TA, at least below 80, but probably not below 60. A lower TA should help reduce the tendency of the pH to rise. Also, try a target pH of 7.7 as the pH will rise less at lower TA and higher pH.

Also, what is your chlorine and shock regimen (how much, how often)?

Richard

Thanks for the response, Richard. The TA tested out at 100ppm and is supposed to be 120-150 according to the guidelines for my spa. It had been 120 ppm before I added the Ph decreaser. The Ph has been 7.8 or higher for a while, regardless of the decreaser I add.

For my chlorine and shock regimen, I add 1 cap chlorine every other week and 1 cap non-chlorine shock every week. The spa has a vision cartridge (silver) and an ozone filter. I was told this would help lessen the need for sanitizers. Should I keep trying to bring the Ph down even if the TA will go lower than recommended. Should I add decreaser every other hour or every other day until it reads properly. Thanks.

I am fascinated by your water maintenance. If you've had your tub since May and haven't had any problems with water quality, that's unreal. I know that the companies that manufacture the silver cartridges suggest low chlorine, but they usually recommend daily dosing with mps. How often do you soak and how many people usually soak? How long have you gone between water changes. Sorry to give you the 5th degree, but this is interesting.

I forgot to ask what temperature the spa should be set at when I am away on business. I have been leaving it at 99 degrees all winter, 24/7 and adding sanitizers in between trips.

I primarily use my hot tub on the weekends, so during the week I keep it down at 90 degrees... my (very basic) understanding is that the "operating temperature" for a hot tub is at least 85 degrees, so you definitely want to keep it above that... not sure if this makes sense or not- I've actually been really curious as to whether it uses more energy to heat from 90 back to 102 on the weekends, or to keep it at 101 or whatever all the time... logic dictates that it would save energy keeping it down, but I'm not sure. Anyone else?

Tony

[Vermonter]

Also, new problem for me: my pH just seems to like to "hang out" at 8.0, maybe a little lower (7.7 to 7.9 at the lowest)... no matter how much acid I add (I've added an entire quart in the past few days), it always seems to end up there again.... my TA has been on the low side of the normal range (somewhere in the low 80's). Richard has told me that MPS will lower my pH... my question is: how bad is this? Is it going to damage my equipment very quickly, or should I just wait for the MPS and Br to bring the level down to an acceptable range?

Tony

[Hillbilly Hot Tub]

Also, new problem for me: my pH just seems to like to "hang out" at 8.0, maybe a little lower (7.7 to 7.9 at the lowest)... no matter how much acid I add (I've added an entire quart in the past few days), it always seems to end up there again.... my TA has been on the low side of the normal range (somewhere in the low 80's). Richard has told me that MPS will lower my pH... my question is: how bad is this? Is it going to damage my equipment very quickly, or should I just wait for the MPS and Br to bring the level down to an acceptable range?

Tony

what we have learned is that it does not save alot to turn the tub down much.(my dad worked foe PSNH) It takes the same amount of electricity to keep a tub maintained at 102 than at 90. the tub senses the heat has dropped 1 degree, be it to 89 or 101 and turns the heat on to bring it back up. takes the same electricity to bring it up 1 degree no matter if its to 90 or 102. When you turn it down it does not heat untill it reaches below the 90 degree mark, but it has to work to bring it back up to the 102. The other reason we have people keep the temps up is when you live in the northeast, have a storm, power is out and tub started at 90 its that much closer to the freezing point. If it is kept at 102, than it takes longer for it to get to the freezing point, just keep the cover shut.

For you PH being high, I still think you have a mineral issue...scale from vermont is quite frequently lime and this would cause a higher PH. High PH causes scale.. Just a thought, but it goes along with your bromine being chewed up too. Seems to be going hand and foot to me.

[chem geek]

So long as your pH remains above 7.0 and indeed above 7.5 most of the time, your equipment will be fine. So let the TA drop more which it will over time as you add acid to lower the pH. As the TA drops, it will take less acid to lower the pH, so just watch that so you don't drop the pH too far.

I'm not sure I follow what Hilbilly Hot Tub said about "scale from vermont is frequently lime and this would cause a higher pH." I know that limestone is calcium carbonate so adding that would be like adding pH Up and would cause both pH and TA to rise. But I don't understand where that is presumably coming from -- fill water that's high in pH and TA? That doesn't explain to me the continued pH rise since I don't think there's anything getting added to this tub except for chlorine and MPS. So the only thing that would make the pH rise would be outgassing of carbon dioxide. Plaster curing will cause pH rise, but this isn't a new plaster spa.

Also, how does minerals (calcium? what minerals) use up bromine? I'm missing the connection.

Richard

[waterbear]

Richard,

"Lime" is a common term for naturally occuring hydroxides, oxides and carbonates of calcium. I guess he was implying that the water in that area has a high calcium content and as you know high calcium levels and high pH do lead to scaling. ALL scale is calcium carbonate as you well know and this certainly does fall under the definintion of 'lime'. However, I know of no way that they will cause bromine levels to decrease!

HOWEVER, vermonter's pH 'hanging out' around 8.0 makes me think that possibly there is some interference to the phenol red from high sanitizer levels since he stated that he added a quart of acid and it had not effect. I would like to know exactly how high the sanitizer levels were when he tested the pH. I suspect the pH is being tested right after shocking.

[Vermonter]

Waterbear-

Nope, not testing right after shocking... it was about 18 hours later, actually. However, the sanitizer levels were fairly high (somewhere around 5.6ppm TC, which is actually Br in this case, so 12.3-ish ppm TB)... by the way, my total hardness readings are right where they should be (on the low side of normal, around 250 ppm), if that helps figure things out. I actually had to add about 10oz. of hardness up when I filled my tub, as it was reading 0ppm (this at the dealer and according to my strips)... Oh, and I'm not using a test kit (yes, yes, I'm going to buy one) using a digital strip reader, and regular strips as a "back up", both read around 8.0 pH, and TA down somewhere around 100.

Tony

[Vermonter]

Also, new problem for me: my pH just seems to like to "hang out" at 8.0, maybe a little lower (7.7 to 7.9 at the lowest)... no matter how much acid I add (I've added an entire quart in the past few days), it always seems to end up there again.... my TA has been on the low side of the normal range (somewhere in the low 80's). Richard has told me that MPS will lower my pH... my question is: how bad is this? Is it going to damage my equipment very quickly, or should I just wait for the MPS and Br to bring the level down to an acceptable range?

Tony

what we have learned is that it does not save alot to turn the tub down much.(my dad worked foe PSNH) It takes the same amount of electricity to keep a tub maintained at 102 than at 90. the tub senses the heat has dropped 1 degree, be it to 89 or 101 and turns the heat on to bring it back up. takes the same electricity to bring it up 1 degree no matter if its to 90 or 102. When you turn it down it does not heat untill it reaches below the 90 degree mark, but it has to work to bring it back up to the 102. The other reason we have people keep the temps up is when you live in the northeast, have a storm, power is out and tub started at 90 its that much closer to the freezing point. If it is kept at 102, than it takes longer for it to get to the freezing point, just keep the cover shut.

For you PH being high, I still think you have a mineral issue...scale from vermont is quite frequently lime and this would cause a higher PH. High PH causes scale.. Just a thought, but it goes along with your bromine being chewed up too. Seems to be going hand and foot to me.

Hmm, it makes sense that it would take the same amount of electricity to increase the heat 1 degree- however, I would think keeping the tub at a higher setting would make the computer request heat more often than if you kept it at a lower setting. However, like you said, this savings might be lost when I go to heat it up to 102 at the end of the week... any physicists/electrical engineers out there?

Tony

[Hillbilly Hot Tub]

Richard,

"Lime" is a common term for naturally occuring hydroxides, oxides and carbonates of calcium. I guess he was implying that the water in that area has a high calcium content and as you know high calcium levels and high pH do lead to scaling. ALL scale is calcium carbonate as you well know and this certainly does fall under the definintion of 'lime'. However, I know of no way that they will cause bromine levels to decrease!

HOWEVER, vermonter's pH 'hanging out' around 8.0 makes me think that possibly there is some interference to the phenol red from high sanitizer levels since he stated that he added a quart of acid and it had not effect. I would like to know exactly how high the sanitizer levels were when he tested the pH. I suspect the pH is being tested right after shocking.

Thank you for exsplaining lime for me to chem geek. My thought was that this tub was used and had a previous scale issue as he stated it was coated all over the old filter. As the tub runs, the scale that has attached inside the lines, on the heater ect. starts to dissole and dissipate into the water causing the PH rise. Sorry I did not clarify myself, being from the area I know that the water around here that has issues with lime also has alot of metals such as iron, gold, ect. This tends to chew up bromine (deplete it) I try to write things in laymans terms, not so scientific or it becomes very confusing to the customer and sometimes myself. I will be attending a spa/pool show in Atlantic City again in a couple of weeks and have been writing down many questions I have for the chemist that are doing some of the water chemistry classes. It will be interesting to see what these people have to say since they specialize in pool and spa water chemistry, specially about using household bleach since they are the ones that help the spa manufactures come up with the reasons why they would void a warrenty.

[Hillbilly Hot Tub]

Also, new problem for me: my pH just seems to like to "hang out" at 8.0, maybe a little lower (7.7 to 7.9 at the lowest)... no matter how much acid I add (I've added an entire quart in the past few days), it always seems to end up there again.... my TA has been on the low side of the normal range (somewhere in the low 80's). Richard has told me that MPS will lower my pH... my question is: how bad is this? Is it going to damage my equipment very quickly, or should I just wait for the MPS and Br to bring the level down to an acceptable range?

Tony

what we have learned is that it does not save alot to turn the tub down much.(my dad worked foe PSNH) It takes the same amount of electricity to keep a tub maintained at 102 than at 90. the tub senses the heat has dropped 1 degree, be it to 89 or 101 and turns the heat on to bring it back up. takes the same electricity to bring it up 1 degree no matter if its to 90 or 102. When you turn it down it does not heat untill it reaches below the 90 degree mark, but it has to work to bring it back up to the 102. The other reason we have people keep the temps up is when you live in the northeast, have a storm, power is out and tub started at 90 its that much closer to the freezing point. If it is kept at 102, than it takes longer for it to get to the freezing point, just keep the cover shut.

For you PH being high, I still think you have a mineral issue...scale from vermont is quite frequently lime and this would cause a higher PH. High PH causes scale.. Just a thought, but it goes along with your bromine being chewed up too. Seems to be going hand and foot to me.

Hmm, it makes sense that it would take the same amount of electricity to increase the heat 1 degree- however, I would think keeping the tub at a higher setting would make the computer request heat more often than if you kept it at a lower setting. However, like you said, this savings might be lost when I go to heat it up to 102 at the end of the week... any physicists/electrical engineers out there?

Tony

The idea behind this is that the outside air is so much colder that it drops from 90 to 89 just as quickly as 102 to 101, the the computer is requesting at the same intervals. It is the intial heating of the water that takes the most juice. I have an economy mode on my tub. It allows me to have the tub only come on to heat dueing filter cycles. This happens 2x per day. My tub drops about 3-4 degrees between filter cycles. Having this on has made no difference in my electric bill as of yet. I have tried it several different times in the past 3 years at different outside temps. Maybe it is because my tub is so well insulated that I do not lose much heat I am not sure, but like I said before, our biggest concern in this area is the power going out in fridgid weather and having the tubs that much closer to freezing, specially where alot of these are second homes and no one is there to notice for a week. I would love to hear from someone in the electrical department too besides my dad, anyone out there??

[waterbear]

Richard,

"Lime" is a common term for naturally occuring hydroxides, oxides and carbonates of calcium. I guess he was implying that the water in that area has a high calcium content and as you know high calcium levels and high pH do lead to scaling. ALL scale is calcium carbonate as you well know and this certainly does fall under the definintion of 'lime'. However, I know of no way that they will cause bromine levels to decrease!

HOWEVER, vermonter's pH 'hanging out' around 8.0 makes me think that possibly there is some interference to the phenol red from high sanitizer levels since he stated that he added a quart of acid and it had not effect. I would like to know exactly how high the sanitizer levels were when he tested the pH. I suspect the pH is being tested right after shocking.

Thank you for exsplaining lime for me to chem geek. My thought was that this tub was used and had a previous scale issue as he stated it was coated all over the old filter. As the tub runs, the scale that has attached inside the lines, on the heater ect. starts to dissole and dissipate into the water causing the PH rise. Sorry I did not clarify myself, being from the area I know that the water around here that has issues with lime also has alot of metals such as iron, gold, ect. This tends to chew up bromine (deplete it) I try to write things in laymans terms, not so scientific or it becomes very confusing to the customer and sometimes myself. I will be attending a spa/pool show in Atlantic City again in a couple of weeks and have been writing down many questions I have for the chemist that are doing some of the water chemistry classes. It will be interesting to see what these people have to say since they specialize in pool and spa water chemistry, specially about using household bleach since they are the ones that help the spa manufactures come up with the reasons why they would void a warrenty.

Metal ions (including calcium) do not cause sanitizer demand. Please do ask the chemists to expalin how metal ions can 'deplete' bromine. It should be interesting. You might also want to ask them their thoughts on the use of 'liquid chlorine" or sodium hypochlorite as a chlorine source or whether calcium hypochorite is ok for spa use (It is marketed for this purpose by at least one MAJOR manufacurer.) Is lithium hypochorite the only unstabilized chlorine source that is ok? Funny how it's also the most expensive. In some areas dichlor is illegal in commercial hot tubs so what alternatives are there for chlorination?

Scale (calcium carbonate) is relatively insoluable and as pH rises more will precipitate out of the water and deposit. Higher temperatures also increase the tendency to scale. The fact that both high pH and high tempeature of the water are the 1st and second most important factors in prediciting scaling can be seen by just looking at the SI equation in which pH and then temperature changes have the greatest impact on the results of the equation while changes in TA and CH have the least since they are used as the log(base10) of the measured value so very large changes in either factor result in very small chages in the SI.

Spas have a tendency toward scaling since the water is kept at an elevated temperature and the constant aeration from the jets and bubblers tends to cause pH to rise because of the outgassing of carbon dioxide, expecially when the fill water has a high calcium content (which you refer to as 'lime'.)

[waterbear]

Waterbear-

Nope, not testing right after shocking... it was about 18 hours later, actually. However, the sanitizer levels were fairly high (somewhere around 5.6ppm TC, which is actually Br in this case, so 12.3-ish ppm TB)... by the way, my total hardness readings are right where they should be (on the low side of normal, around 250 ppm), if that helps figure things out. I actually had to add about 10oz. of hardness up when I filled my tub, as it was reading 0ppm (this at the dealer and according to my strips)... Oh, and I'm not using a test kit (yes, yes, I'm going to buy one) using a digital strip reader, and regular strips as a "back up", both read around 8.0 pH, and TA down somewhere around 100.

Tony

First of all, total hardness is a bogus reading which is one reason why strips are not that useful. You are interested in calcium harndess since calcium is what causes scale deposits. Total hardness is a combination of calcium and magnesium hardness. Magnesium does not produce scale.

How important high CH is depends mostly on the material your tub is made of. Acrylic and fiberglass tubs only really need around 150 ppm CH and that is really mostly because hard water has less of a tendency to foam then soft water. A plaster spa or one with grouted tilework would need a higher CH, usually between 200-400 to protect the plaster from surface damage. If you are worried about metal parts such as your heat exchanger, pH is the main factor in whether they will suffer any corrosion or not. Just make sure to keep yours above 7.2 at all times.

High sanitizer levels will interfere with pH testing. Levels above about 10 ppm will cause the pH to read high. I would be interested in knowing what your pH reads with a drop based test when the sanitizer levls are within normal range (say about 4-6 ppm total bromine, not free bromine, as tested with either OTO or DPD testing). If your total bromine is above about 10 ppm then I would look at the pH readigs you are getting as suspect.

You can actually get much more accurate sanitizer and pH readings from a $7 Taylor K-1000 pH/OTO test kit for these two measurements then you can from strips in a $600 strip scanner. At least it would get two of your measurments more under control. IMHO, the best testkit for a bromine system for home use is a Taylor K-2106. It really does make water balancing so much easier and it's much easier to read than strips. ( and no guessing as to whether the TA is closer to the 80 ppm or the 120 ppm block. Strips just don't have the precision needed for balancing water.)

[chem geek]

Thanks waterbear and Hillbilly Hot Tub for explaining it to me. I had totally missed that there was or could have been pre-existing scale (calcium carbonate) which, of course, when dissolving into water not saturated with calcium carbonate would raise the pH (with some increase in CH and TA as well, if acid were not added). I, like waterbear, don't see the mechanism where the metals deplete bromine. Hillbilly Hot Tub: ask the chemist about that mechanism and also about the bleach, specifically letting him/her know that it's not only bleach to be used, but Dichlor initially to build up some CYA level first.

Richard

[Vermonter]

Waterbear-

Nope, not testing right after shocking... it was about 18 hours later, actually. However, the sanitizer levels were fairly high (somewhere around 5.6ppm TC, which is actually Br in this case, so 12.3-ish ppm TB)... by the way, my total hardness readings are right where they should be (on the low side of normal, around 250 ppm), if that helps figure things out. I actually had to add about 10oz. of hardness up when I filled my tub, as it was reading 0ppm (this at the dealer and according to my strips)... Oh, and I'm not using a test kit (yes, yes, I'm going to buy one) using a digital strip reader, and regular strips as a "back up", both read around 8.0 pH, and TA down somewhere around 100.

Tony

First of all, total hardness is a bogus reading which is one reason why strips are not that useful. You are interested in calcium harndess since calcium is what causes scale deposits. Total hardness is a combination of calcium and magnesium hardness. Magnesium does not produce scale.

How important high CH is depends mostly on the material your tub is made of. Acrylic and fiberglass tubs only really need around 150 ppm CH and that is really mostly because hard water has less of a tendency to foam then soft water. A plaster spa or one with grouted tilework would need a higher CH, usually between 200-400 to protect the plaster from surface damage. If you are worried about metal parts such as your heat exchanger, pH is the main factor in whether they will suffer any corrosion or not. Just make sure to keep yours above 7.2 at all times.

High sanitizer levels will interfere with pH testing. Levels above about 10 ppm will cause the pH to read high. I would be interested in knowing what your pH reads with a drop based test when the sanitizer levls are within normal range (say about 4-6 ppm total bromine, not free bromine, as tested with either OTO or DPD testing). If your total bromine is above about 10 ppm then I would look at the pH readigs you are getting as suspect.

You can actually get much more accurate sanitizer and pH readings from a $7 Taylor K-1000 pH/OTO test kit for these two measurements then you can from strips in a $600 strip scanner. At least it would get two of your measurments more under control. IMHO, the best testkit for a bromine system for home use is a Taylor K-2106. It really does make water balancing so much easier and it's much easier to read than strips. ( and no guessing as to whether the TA is closer to the 80 ppm or the 120 ppm block. Strips just don't have the precision needed for balancing water.)

Thanks for your time, once again. Do you have a link for the Taylor K-2106? I saw in another post of yours a link for the Cl based kit, went to that site, and couldn't find the 2106... if you have a link handy, that would be great.

Now, since I know for a fact my TH was 0 ppm (or darn near) when I filled the tub, and all I added was Calcium Carbonate (I think that's what it is, right? Anyway, the Ca-based TH raiser), then I know that my TH is entirely Ca-based... so... at least I have that going for me The strips have to be reading only Ca on the hardness pad, correct? That's the only one that has remained constant since I filled the thing, so please don't tell me I have to worry about that one, too!!

Also, I agree about the accuracy issues, even with the strip reader... the TA tends to be all over the place, even on back-to-back reads, but for whatever reason the pH seems to be, if not accurate (since I have no baseline to compare, I guess), at least consistent. In other words, two back to back readings tend to get the same pH numbers, while the TC and TA readings tend to be a bit more hit or miss.

That being said... I added 8 oz. pH down, and the last reading I took was pH of 7.4 and TA of 119, TC of 3.2 ... I almost added another 4 oz of pH down just to get the TA down a little more, and I stopped myself at the last second, thinking: "if it ain't broke, don't fix it"!

Tony