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

[chem geek]

TinyBubbles, I think wireman's description of a lot of pH down was referring to his lowering of the TA where that was accomplished by a combination of intentional aeration at lower pH with acid addition. Once at the lower TA, the pH rise was less or close to stable, BUT this also required doing less aeration on an ongoing basis. I'm not sure what his sources of aeration are or if you will be able to do this same. If it's an ozonator, then having that off more often would probably help. If it's the jets in the spa, then turning off their air probably helps as well though obviously can change the "experience" of the spa (though all jets clearly won't need air in them -- only the ones you are using and only if you really want with air in them). Also, thanks for clarifying the CCs showing up with MPS. That helps explain what you saw. You've been doing a lot of experimenting so I get confused sometimes with what's been done.

wireman, yes the Combined Chlorine (CC) should break down from bleach alone. You shouldn't need to shock with bleach assuming you use enough on a daily basis (if the spa is used every day), but it takes quite a lot as a regular dose (roughly 7 ppm FC per person-hour in 350 gallons, as a rough estimate) if you don't use MPS as you don't want to run out in the middle of breaking down CCs. By having a lower CYA level, the CCs should break down more quickly, though it still takes hours depending on how much ammonia/urea there is. It's better to use more chlorine than you need and ensure you have a residual rather then the other way around. There are some organics, in much smaller quantities unless you use lotion (or makeup), that are slower to form CCs and are also harder to get rid of once they are formed. MPS is useful for these as it will oxidize them before chlorine gets a chance to combine with them. So a very reasonable routine is to add a relatively large dose of MPS when you get out, let it mix for a bit (unfortunately, I don't know for how long -- probably not too long, under an hour, maybe just 5 minutes) to oxidize the ammonia/urea and the tougher organics, then add chlorine later. This should use far less chlorine overall. There are other options such as the one where chlorine is added the next morning, but you get the idea.

If one doesn't use MPS at all and doesn't have an ozonator, then it's quite possible some CC might show up and shocking with chlorine could help get rid of it, but realistically if one cannot keep the CC near zero with regular addition of chlorine, then MPS is advisable. In a pool, chlorine alone works fine, but in a spa the bather load is so much higher (and there's no sunlight) so supplementing with MPS may be a necessity. This is just speculation on my part as I don't think we have enough "pure chlorine" users to determine whether MPS is a necessity or just a nice supplement to reduce chlorine usage.

Richard

[JackVa1]

I am reading things in this thread about using an ozonator. Is the use of an Ozonator optional? I thought it was a requirement since all tubs come with them. What am I missing?

Still waiting to know what the Frog wil do for me when my Spa arrives also. If it's worthless, I need to know that.

Patiently waiting for spa to be delivererd and chemicals information. Sounds like all this testing is going to be occupying my life shortly and I am not looking forward to it.

Jack

[TinyBubbles]

Good news, my ph came has come down with the use of dichlor and MPS. Armed with wireman's info. I bought a new bottle of ph down and headed home. I got out my test kit to test the ph and start adjusting like crazy and couldn't believe it when it said 7.6. I restested and used test strips and sure enough, it's in the normal range finally. Anyone need an unopened bottle of ph down?

Jack, ozonators are optional. I believe your spa frog is a mineral cartridge and maybe your bromine dispenser, is that right? Ozonators and mineral cartridges are methods of sanitizing and oxidizing your water. There is much debate on their usefullness as you've probably witnessed on this forum. I think the main objective of both of them is to lower the amount of chemicals you need to use to keep your water clean and healthy.

[wireman]

Tiny, I don't want you to think I added all that PH down at once. That would make for some nice acid in my tub : ) I've stopped aerating the tub all the time right now. But think that just not aerating when your not in it would do the same thing. I think what was happening was that there was something in the water that with aeration was upping the PH. I think adding PH down over a prolonged time has removed whatever was in the water or minimized it. I also think not aerating when not in helps with my power bill and keeping water in the tub.

I don't have an ozonator and and treating the CC's with MPS right before adding chlorine and jumping in maybe 20 min later. I don't think it really matters when i add the MPS but I'm probably maintaining some FC because the MPS is doing the job the chlorine would be doing. Maybe I'll cut back on the MPS use and try a little more chlorine?

I'd save that bottle of PH down. You'll need it next time you drain and refill : )

[chem geek]

wireman is correct. The "thing" in the water that makes the pH rise with aeration is carbon dioxide including bicarbonate. Pools and spas are intentionally over-carbonated, just like a beverage though clearly not as bubbly! If you blow bubbles (i.e. aerate) in a carbonated beverage, it will go flat faster. If you were to measure the pH of a carbonated beverage that you make flat, you would find that it becomes less acidic (i.e. pH rises). Total Alkalinity (TA) is mostly a measure of the amount of bicarbonate in the water so at a given pH it is a rough measure of the total amount of dissolved carbon dioxide in the water in all of its forms.

Aeration drives carbon dioxide out of the water faster. The concentration of carbon dioxide in the water is much higher than that in air so it WANTS to leave the water. Aeration just makes that go faster. It also outgasses faster at lower pH levels which is why the TA lowering procedure (see this post) has one lower the pH and aerate the water while continuing to add acid. In wireman's case, he added acid more slowly over time, but the net effect is the same: a lowering of TA.

Aeration speeds up carbon dioxide outgassing and this makes the pH rise with no change in TA. Then when you add acid, you lower both pH and TA with the net result of these two processes being a lowering of TA. Eventually, the TA gets so low that the rate of outgassing is noticeably lower and this has the pH rise more slowly. Reducing the aeration also helps reduce this rate of outgassing.

Your fill water may be high in TA. If it's more than 60 or so, then what wireman is saying is that initially you will see more of a rise in pH so you'll need the acid. You can accelerate the process and get it over with all at once by lowering the pH, aerating vigorously, and add acid to keep the pH low (around 7.0) until the TA drops to say 50 or 60. Then you just continue to aerate without adding acid to get the pH up to 7.5 or so. It's a pay-me-now or pay-me-later sort of situation. You will end up adding the same amount of acid either way to get the TA lower -- the procedure I just described just speeds up the process.

Richard

[TinyBubbles]

Tiny, I don't want you to think I added all that PH down at once. That would make for some nice acid in my tub : ) I've stopped aerating the tub all the time right now. But think that just not aerating when your not in it would do the same thing. I think what was happening was that there was something in the water that with aeration was upping the PH. I think adding PH down over a prolonged time has removed whatever was in the water or minimized it. I also think not aerating when not in helps with my power bill and keeping water in the tub.

I don't have an ozonator and and treating the CC's with MPS right before adding chlorine and jumping in maybe 20 min later. I don't think it really matters when i add the MPS but I'm probably maintaining some FC because the MPS is doing the job the chlorine would be doing. Maybe I'll cut back on the MPS use and try a little more chlorine?

I'd save that bottle of PH down. You'll need it next time you drain and refill : )

That is the picture I had. You dumping all that in at once! I'm glad my ph came down or I was about to do that. My tap water has a low ph so I have to add PH UP when I fill the tub. Until using bleach, I had never even opened the little packet of PH DOWN that came with my start up kit. Oh well, atleast the stuff is cheap. With the exception of the bubbles from my ozonator 12 hours a day, there is no other aeration when we aren't using the tub. We always turn the air off when we get out and my jets only turn on 2 minutes at the start of each filter cycle to purge the lines. I'm curious to see how long my PH stays in the desired range or if it will continue to drop. Before using bleach I added a little PH UP every saturday. By the following weekend it started to drop a little again. I'm ok with weekly additions, but the daily attempts to lower the ph were just too much. It's funny that they consider water chemistry a science, because it doesn't seem very exact. It seems like all of us have to find what works for us. Whether our water is different, differences in our spas or differences in our body chemistry and lifestyle add different things to the water: something prevents there from being one tried and true method. Right now I'm pretty happy with the small amount of MPS and dichlor I'm using. I hope they don't fail me.

[wireman]

It is science but we aren't scientist! (except for ChemGeek and Waterbear) : ) Tiny perhaps you added something to adjust the total alkalinity up? I'm seeing no PH rise from using bleach which has been substantiated in some other posts in the past I believe?

[104 Degrees]

It is science but we aren't scientist! (except for ChemGeek and Waterbear) : ) Tiny perhaps you added something to adjust the total alkalinity up? I'm seeing no PH rise from using bleach which has been substantiated in some other posts in the past I believe?

I had the PH rise

[TinyBubbles]

It is science but we aren't scientist! (except for ChemGeek and Waterbear) : ) Tiny perhaps you added something to adjust the total alkalinity up? I'm seeing no PH rise from using bleach which has been substantiated in some other posts in the past I believe?

I didn't add anything to raise my alkalinity. I did add product to lower it at the suggestion that it could help my high ph problems. Wireman, when you had your high ph and had to add so much ph down, what were you using as your sanitizer?

104, have you managed to get your ph down and keep it down while using bleach?

[104 Degrees]

It is science but we aren't scientist! (except for ChemGeek and Waterbear) : ) Tiny perhaps you added something to adjust the total alkalinity up? I'm seeing no PH rise from using bleach which has been substantiated in some other posts in the past I believe?

I didn't add anything to raise my alkalinity. I did add product to lower it at the suggestion that it could help my high ph problems. Wireman, when you had your high ph and had to add so much ph down, what were you using as your sanitizer?

104, have you managed to get your ph down and keep it down while using bleach?

I did not get to the bleach.I dumped my tub Jan 1st and have been using the dichlor.I have been keeping up to 5 or a little less. it will be in the threes the next morning. So far so good.I do belive alot of my problems was with the scent. it must have soap in it that made my rash worse. I just added for the first time Wendsday a table spoon of shock. I went in this morning with no problems so far.I also have been using cream after i shower and its been helping.i do use a once of spa brite each week.

I will get back to you on this at the end of the month or sooner if something develops.

104 degrees

[wireman]

Bottom line I"ve seen the chemical process of adding bleach broken down on this site somewhere. It doesn't noticeably raise your PH.

[chem geek]

Bottom line I"ve seen the chemical process of adding bleach broken down on this site somewhere. It doesn't noticeably raise your PH.

wireman, do you have an ozonator? If not, then perhaps that might explain the difference in your situation and TinyBubbles. If the ozonator is aerating the water, then this is similar to your situation before you turned off the air in your jets and experienced pH rise. Nevertheless, the situation TinyBubbles has is unusual in ways that are yet to be explained such as why the bleach that is used gets used up more quickly than the Dichlor (when switching between the two, so at comparable CYA levels). Perhaps the specific bleach being used has more lye in it, but the contents of Clorox Regular and some off-brand Ultra bleaches show very little lye and are consistent with minimal pH rise.

The overall chemical reactions with any hypochlorite source of chlorine are shown in this post. The addition of hypochlorite makes the pH rise, but the usage of the chlorine (mostly breaking down urea and ammonia in spas) is acidic and exactly compensates. However, if chlorine is outgassed (as hypochlorous acid), then this would cause pH to rise and if the water is salty (higher chloride content) and outgasses chlorine gas, then this raises the pH even more though is unlikely since the reaction to produce chlorine gas is relatively slow. Aeration could make the outgassing happen faster.

Dichlor is near pH neutral when added to water so after the usage of chlorine (which is acidic) the net result is acidic. So if other factors, such as aeration of carbon dioxide or chlorine, cause the pH to rise, then the net acidity of Dichlor makes the pH stable (though the TA will drop slowly over time).

Richard

[104 Degrees]

Bottom line I"ve seen the chemical process of adding bleach broken down on this site somewhere. It doesn't noticeably raise your PH.

It did for me. I said it in a post here somewhere awhile ago.

[TinyBubbles]

Bottom line I"ve seen the chemical process of adding bleach broken down on this site somewhere. It doesn't noticeably raise your PH.

wireman, do you have an ozonator? If not, then perhaps that might explain the difference in your situation and TinyBubbles. If the ozonator is aerating the water, then this is similar to your situation before you turned off the air in your jets and experienced pH rise. Nevertheless, the situation TinyBubbles has is unusual in ways that are yet to be explained such as why the bleach that is used gets used up more quickly than the Dichlor (when switching between the two, so at comparable CYA levels). Perhaps the specific bleach being used has more lye in it, but the contents of Clorox Regular and some off-brand Ultra bleaches show very little lye and are consistent with minimal pH rise.

The overall chemical reactions with any hypochlorite source of chlorine are shown in this post. The addition of hypochlorite makes the pH rise, but the usage of the chlorine (mostly breaking down urea and ammonia in spas) is acidic and exactly compensates. However, if chlorine is outgassed (as hypochlorous acid), then this would cause pH to rise and if the water is salty (higher chloride content) and outgasses chlorine gas, then this raises the pH even more though is unlikely since the reaction to produce chlorine gas is relatively slow. Aeration could make the outgassing happen faster.

Dichlor is near pH neutral when added to water so after the usage of chlorine (which is acidic) the net result is acidic. So if other factors, such as aeration of carbon dioxide or chlorine, cause the pH to rise, then the net acidity of Dichlor makes the pH stable (though the TA will drop slowly over time).

Richard

But, I have the same ozonator when I use dichlor and no ph rise. So it wouldn't make sense that it's the ozonator. I've searched the forum and found numerous entries on this and the pool forum where people report a rise in their ph with the use of bleach. I've gone to multiple chemical websites and they all state that the ph of water will rise if you add bleach. In fact, they state it's one of the main reasons that bleach breaks down in water. The ph of the bleach is lowered as it disperses into the water and at the same time the ph of the water is raised. Since the ph of the water isn't raised as high as the original ph of the bleach, they suggest adding something to raise the ph of the water if you are using the bleach to disinfect drinking water, because sodium hypochlorite breaks down rapidly at a lower ph and is not as effective. It should be a simple theory to test. This weekend I will put water in a bucket, test the ph and then add bleach. If the ph is raised, then we have the answer. "Liquid chlorine is another type which is created by bubbling the chlorine gas through a solution of caustic soda. The yellow liquid (stronger, but chemically identical to bleach) has 10 - 15% available chlorine, and has a pH on the other end of the scale at 13. Liquid Chlorine is called Sodium Hypochlorite (NaOCl), and because it is already in solution, sodium-hypo produces hypochlorous acid instantly when it contacts water. The liquid can be poured directly into the pool but it is recommended to use a diaphragm or peristaltic pump. The use of liquid chlorine is more dominant in larger commercial pools which have it delivered into 55 gallon vats. For most residential pools, the lower cost seems to be outweighed by its difficulty in use and the amount of acid required to counteract its pH of 13. Use care when handling as this chemical is corrosive to just about everything." This statement was found at poolcenter.com under the heading "chlorine chemistry". If someone wants to use bleach, that's certainly their decision. But I believe they need the correct information to make their decision.

Here is information I've found: "The alkalinity (ph) of the sodium hypochlorite solution causes the precipitation of minerals such as calcium carbonate, so that shock chlorination is often accompanied by a clogging effect. The precipitate also preserves bacteria, making this practice somewhat less effective." So then I research precipitated calcium carbonate and find this: "In water, PCC (precipitated calcium carbonate) forces the pH to 8 or higher." Is this scale building up in our plumbing lines and jets when using bleach? We've all been warned that is is something to worry about. "Household bleach and pool chlorinator solutions are typically stabilized by a significant concentration of lye (caustic soda, NaOH)". " Caustic soda forms a strong alkaline solution when dissolved in a solvent such as water." In addition, most ph up products for spas have a ph of 8.2. Why would one assume that these products would raise the ph, but bleach with a ph of atleast 11 would not? We are using alot more bleach than the amount of ph up we would use to raise ph.

[104 Degrees]

I do belive now that my problem is the scent and the Shock. I started to icth last night. I will have more soon.I'm going to have my CYA tested at the end of the month.

[chem geek]

Bleach is basic (alkaline) so makes the pH rise and I've never said that it didn't when only looking at the addition of chlorine and not its usage. If you measure the pH of bleach, it is very high -- that is not in dispute. Dichlor is very slightly acidic (in normal quantities added to a spa) so is close to pH neutral. BUT chlorine just doesn't sit in the water and build up over time with the addition of bleach or Dichlor. The chlorine gets used up and this is an acidic process. So the NET result of bleach is pH neutral and with Dichlor it is acidic. The reason you see a pH rise when using bleach and pH fairly neutral when using Dichlor is that you have another source of rising pH.

So do an experiment, but not the one you proposed since it won't prove anything that we don't already know -- we know bleach and chlorinating liquid are high in pH -- 6% bleach is around pH 11.4 while 12.5% chlorinating liquid is around pH 12.5. The experiment to do is simply not add any chemicals (no Dichlor, bleach, MPS) to the spa, but keep the ozonator running and use the jets as you normally would, uncover the spa for as long as you normally do, but don't get into the spa as it won't be as sanitized (though with the ozonator it's not as bad as it could be). Notice what happens to the pH. If it rises, then you have a source of rising pH and that's what we've been trying to determine to see if it can be reduced. I believe it's the aeration driving carbon dioxide out of the water since that makes the pH rise.

If you wanted to do an experiment in a bucket that was closer to what happens in a spa, then you would add bleach, but then add some ammonia in an amount to use up the chlorine. The pH of the water will rise when the bleach is added, but it will fall when the ammonia is added after some time (if you measure the pH of the ammonia added to water separately, it will be high in pH). However, if you don't have some sort of test strip or pH meter with a broad measurement range, then you won't be able to see this very well. The pH in pool/spa test kits assumes you are measuring in the range of roughly 7.0 to 8.0.

As far as bleach breaking down in water, they are talking about concentrated solutions, not dilute solutions as in a pool or spa. The breakdown is much, much slower at lower concentrations. Look again at the table at the bottom of this link and notice that the rate of degradation of chlorine in water is roughly proportional to the square of the concentration. Clorox Regular bleach at 6% is roughly 60,000 ppm. The concentration in a spa is at most 10 ppm so the difference in rates of breakdown are (60,000/10)^2 = 36 million! The other factor you can see in the table is temperature where where a 10F increase results in a little more than doubling of the rate of degradation so at 104F compared to say 74F that's 30F or perhaps a factor of 2^(30/10) = 8 so say 10 difference. So the higher spa temperatures would degrade concentrated chlorine faster, but a factor of 10 increase due to the temperature is completely undone by the factor of 36 million decrease from the dilution.

The part you quoted about using chlorinating liquid in pools and the cost of acid being required is baloney. I've posted to poolcenter.com before and though most of what is said is reasonable, some things like that are just untrue. The only time you need to add a lot of acid in a pool when using chlorinating liquid is when the TA level is high or you have lots of aeration. What you are quoting is just one of the many falsehoods the pool and spa industry continue to believe because they haven't looked at the science and/or they are promoting their own sales agenda -- in the case of poolcenter.com, they are just repeating a false assumption based on the high pH of the source of chlorine and seeing a rise in pH for reasons they do not understand but are due to high TA and aeration. There are hundreds of pool users at The Pool Forum and at TroubleFreePool who use only bleach or chlorinating liquid as their chlorine source in their pools and their pH is stable. The only exceptions have been those with high TA, those with aeration features such as waterfalls, spillovers, fountains and those with SWG systems since those produce hydrogen gas bubbles that aerate the water. Even in these latter cases, a lowering of TA and finding ways to lower SWG output have helped reduce the rate of pH rise. See this thread for an extreme example of how lower TA eliminated a pH rise problem and this long thread which is when we first started figuring this all out. I only add 12.5% chlorinating liquid to my pool at a rate that if the chlorine didn't get used up would raise the pH from 7.5 to 7.8 in just one week (with 1 ppm FC required per day). My pool has an opaque safety cover, but during the summer gets used almost every day for about 1 to 1.5 hours (so is exposed during that time). The pH is rock solid and does not climb. I keep the TA at 80 or so when possible and if I didn't have the cover I'd probably target an even lower TA.

As for precipitation of calcium carbonate, that does occur more at higher pH, but only if you have calcium and carbonate to precipitate. Calcium is measured in Calcium Hardness while carbonate comes from Total Alkalinity and higher pH. Having high pH alone will not precipitate calcium carbonate. If the TA is lower and the CH is lower, you won't get calcium carbonate even at higher pH. I never said you should target a pH of 8 or more when using bleach. Targeting a pH of 7.7 is reasonable. [EDIT] I change this recommendation in a later post in this thread where I say that 7.5 would be more conservative to prevent the pH from getting above 8 right after bleach addition and before it gets used up. [END-EDIT] There is no question that if you don't resolve the pH rise and don't want to add acid to keep the pH to a reasonable range then this isn't good, but that's not what should be done. The part about household bleach and pool chlorinator solutions typically stabilized by a significant concentration of lye is again not true for most bleach and chlorinating liquid. This link is a typical MSDS of chlorinating liquid showing 0.8% lye. Clorox Regular Bleach has an (older) MSDS shown here that lists <1% sodium hydroxide (lye). I have the calculations in my spreadsheet accounting for this extra lye and it has very little effect on pH because the quantity is so small. The main effect on the pH comes not from the extra lye, but from the pH of the bleach solution itself due to it being mostly hypochlorite ion and not hypochlorous acid and this accounts for nearly all of its high pH -- the lye just pushes up the pH a little more to be more stable. (Technically, the pH is just the measure of the amount of hydrogen ion so saying things like how much is due to sodium hypochlorite and how much is due to sodium hydroxide just refers to equivalent sources of pure substances added to water for an "ingredients" weight measurement and comes from the way that the product is manufactured by adding chlorine gas to a solution of lye -- the lye reported on the ingredients list is the "excess" leftover by intentionally not adding a little more chlorine gas to exactly match the initial amount of lye to produce a solution that would be as if one added "pure" sodium hypochlorite to "pure" water).

As for most pH Up products having a pH of 8.2, that is again just baloney since pH Up products such as sodium carbonate are solids so to measure pH they quote what happens when a certain quantity of pH Up is added to a certain quantity of pure water. Obviously, the pH that results depends on the relative amounts of pH Up and water that are used. Again, I have the correct calculations in the spreadsheet that predict what will happen and this also is consistent with the "how much to add per so many gallons" label instructions on such products. In fact, if I add 10 ounces weight of pH Up to 350 gallons of water with an initial TA of 50 and pH of 7.5, then the pH goes up to 10.0, not 8.2 (and the TA goes up to 252 ppm). In fact, one ounce weight of sodium carbonate (pH Up) in one gallon of pure (distilled) water would raise the pH from 7.0 to 11.3. As just one example, look at this MSDS for GLB Rendezvous pH Up where a 1% solution gives a pH of 11-12. [EDIT] I think I know where the pH of 8.2 is coming from. They are probably talking about Alkalinity Up products, sodium bicarbonate or baking soda, since adding this won't get the pH much above 8.0. Of course, selling baking soda as a pH Up product isn't right as it increases TA much more than it increases pH. [END-EDIT]

Richard

[Hillbilly Hot Tub]

Bleach is basic (alkaline) so makes the pH rise and I've never said that it didn't when only looking at the addition of chlorine and not its usage. If you measure the pH of bleach, it is very high -- that is not in dispute. Dichlor is very slightly acidic (in normal quantities added to a spa) so is close to pH neutral. BUT chlorine just doesn't sit in the water and build up over time with the addition of bleach or Dichlor. The chlorine gets used up and this is an acidic process. So the NET result of bleach is pH neutral and with Dichlor it is acidic. The reason you see a pH rise when using bleach and pH fairly neutral when using Dichlor is that you have another source of rising pH.

So do an experiment, but not the one you proposed since it won't prove anything that we don't already know -- we know bleach and chlorinating liquid are high in pH -- 6% bleach is around pH 11.4 while 12.5% chlorinating liquid is around pH 12.5. The experiment to do is simply not add any chemicals (no Dichlor, bleach, MPS) to the spa, but keep the ozonator running and use the jets as you normally would, uncover the spa for as long as you normally do, but don't get into the spa as it won't be as sanitized (though with the ozonator it's not as bad as it could be). Notice what happens to the pH. If it rises, then you have a source of rising pH and that's what we've been trying to determine to see if it can be reduced. I believe it's the aeration driving carbon dioxide out of the water since that makes the pH rise.

If you wanted to do an experiment in a bucket that was closer to what happens in a spa, then you would add bleach, but then add some ammonia in an amount to use up the chlorine. The pH of the water will rise when the bleach is added, but it will fall when the ammonia is added after some time (if you measure the pH of the ammonia added to water separately, it will be high in pH). However, if you don't have some sort of test strip or pH meter with a broad measurement range, then you won't be able to see this very well. The pH in pool/spa test kits assumes you are measuring in the range of roughly 7.0 to 8.0.

As far as bleach breaking down in water, they are talking about concentrated solutions, not dilute solutions as in a pool or spa. The breakdown is much, much slower at lower concentrations. Look again at the table at the bottom of this link and notice that the rate of degradation of chlorine in water is roughly proportional to the square of the concentration. Clorox Regular bleach at 6% is roughly 60,000 ppm. The concentration in a spa is at most 10 ppm so the difference in rates of breakdown are (60,000/10)^2 = 36 million! The other factor you can see in the table is temperature where where a 10F increase results in a little more than doubling of the rate of degradation so at 104F compared to say 74F that's 30F or perhaps a factor of 2^(30/10) = 8 so say 10 difference. So the higher spa temperatures would degrade concentrated chlorine faster, but a factor of 10 increase due to the temperature is completely undone by the factor of 36 million decrease from the dilution.

The part you quoted about using chlorinating liquid in pools and the cost of acid being required is baloney. I've posted to poolcenter.com before and though most of what is said is reasonable, some things like that are just untrue. The only time you need to add a lot of acid in a pool when using chlorinating liquid is when the TA level is high or you have lots of aeration. What you are quoting is just one of the many falsehoods the pool and spa industry continue to believe because they haven't looked at the science and/or they are promoting their own sales agenda -- in the case of poolcenter.com, they are just repeating a false assumption based on the high pH of the source of chlorine and seeing a rise in pH for reasons they do not understand but are due to high TA and aeration. There are hundreds of pool users at The Pool Forum and at TroubleFreePool who use only bleach or chlorinating liquid as their chlorine source in their pools and their pH is stable. The only exceptions have been those with high TA, those with aeration features such as waterfalls, spillovers, fountains and those with SWG systems since those produce hydrogen gas bubbles that aerate the water. Even in these latter cases, a lowering of TA and finding ways to lower SWG output have helped reduce the rate of pH rise. See this thread for an extreme example of how lower TA eliminated a pH rise problem and this long thread which is when we first started figuring this all out. I only add 12.5% chlorinating liquid to my pool at a rate that if the chlorine didn't get used up would raise the pH from 7.5 to 7.8 in just one week (with 1 ppm FC required per day). My pool has an opaque safety cover, but during the summer gets used almost every day for about 1 to 1.5 hours (so is exposed during that time). The pH is rock solid and does not climb. I keep the TA at 80 or so when possible and if I didn't have the cover I'd probably target an even lower TA.

As for precipitation of calcium carbonate, that does occur more at higher pH, but only if you have calcium and carbonate to precipitate. Calcium is measured in Calcium Hardness while carbonate comes from Total Alkalinity and higher pH. Having high pH alone will not precipitate calcium carbonate. If the TA is lower and the CH is lower, you won't get calcium carbonate even at higher pH. I never said you should target a pH of 8 or more when using bleach. Targeting a pH of 7.7 is reasonable. There is no question that if you don't resolve the pH rise and don't want to add acid to keep the pH to a reasonable range then this isn't good, but that's not what should be done. The part about household bleach and pool chlorinator solutions typically stabilized by a significant concentration of lye is again not true for most bleach and chlorinating liquid. This link is a typical MSDS of chlorinating liquid showing 0.8% lye. Clorox Regular Bleach has an (older) MSDS shown here that lists <1% sodium hydroxide (lye). I have the calculations in my spreadsheet accounting for this extra lye and it has very little effect on pH because the quantity is so small. The main effect on the pH comes not from the extra lye, but from the pH of the bleach solution itself due to it being mostly hypochlorite ion and not hypochlorous acid and this accounts for nearly all of its high pH -- the lye just pushes up the pH a little more to be more stable. (Technically, the pH is just the measure of the amount of hydrogen ion so saying things like how much is due to sodium hypochlorite and how much is due to sodium hydroxide just refers to equivalent sources of pure substances added to water for an "ingredients" weight measurement and comes from the way that the product is manufactured by adding chlorine gas to a solution of lye -- the lye reported on the ingredients list is the "excess" leftover by intentionally not adding a little more chlorine gas to exactly match the initial amount of lye to produce a solution that would be as if one added "pure" sodium hypochlorite to "pure" water).

As for most pH Up products having a pH of 8.2, that is again just baloney since pH Up products such as sodium carbonate are solids so to measure pH they quote what happens when a certain quantity of pH Up is added to a certain quantity of pure water. Obviously, the pH that results depends on the relative amounts of pH Up and water that are used. Again, I have the correct calculations in the spreadsheet that predict what will happen and this also is consistent with the "how much to add per so many gallons" label instructions on such products. In fact, if I add 10 ounces weight of pH Up to 350 gallons of water with an initial TA of 50 and pH of 7.5, then the pH goes up to 10.0, not 8.2 (and the TA goes up to 252 ppm). In fact, one ounce weight of sodium carbonate (pH Up) in one gallon of pure (distilled) water would raise the pH from 7.0 to 11.3. As just one example, look at this MSDS for GLB Rendezvous pH Up where a 1% solution gives a pH of 11-12.

Richard

you state that those pools with spillovers, fountains etc. that aerate the water have had issues. This is a very large body of water with what would be a small amount of aeration compared to a spa. Spas with multiple pumps, loads of jets, water falls and fans aerate the water much much more than a pool. Add this with hot water, bather/water ratio, maybe the spa and chemical industry is not full of it, maybe it is just to hard and to much work for the typical spa owner to get correct in their spa so why chance damageing equipment.

Also, I have 3 tubs I deal with, Nature 2 systems. Alk 80, CH 50 and when PH starts to rise (8.0-84), we start seeing scale forming. If left at the high PH to long it starts to stick to the jets and filter pretty bad, never mindwhat it does to the heater! I talked about this in another thread, we have lime in our well water in this area, along with many other minerals, although our calcium hardness is not high when we fill tubs. So what is causing the scale? Is there more chemistry involved that is being missed?

Just still trying to figure all this out....personal curiosity I guess!

[chem geek]

you state that those pools with spillovers, fountains etc. that aerate the water have had issues. This is a very large body of water with what would be a small amount of aeration compared to a spa. Spas with multiple pumps, loads of jets, water falls and fans aerate the water much much more than a pool. Add this with hot water, bather/water ratio, maybe the spa and chemical industry is not full of it, maybe it is just to hard and to much work for the typical spa owner to get correct in their spa so why chance damageing equipment.

Also, I have 3 tubs I deal with, Nature 2 systems. Alk 80, CH 50 and when PH starts to rise (8.0-84), we start seeing scale forming. If left at the high PH to long it starts to stick to the jets and filter pretty bad, never mindwhat it does to the heater! I talked about this in another thread, we have lime in our well water in this area, along with many other minerals, although our calcium hardness is not high when we fill tubs. So what is causing the scale? Is there more chemistry involved that is being missed?

Just still trying to figure all this out....personal curiosity I guess!

I completely get your point and if it weren't for the fact that some people with spas are able to use the Dichlor then bleach approach without a serious pH rise then I'd just say you have to add acid as well as chlorine (not together in concentrated form, or course) to produce the same technical results as are accomplished with Dichlor, but without adding extra CYA. But maybe for some spa situations, that we have yet to precisely determine (i.e. ozonator vs. air in jets vs. jets themselves), if you use bleach then you need to use acid as well. There's also the apparent faster usage of bleach relative not only to Dichlor but also to Lithium Hypochlorite (though the latter could be non-equivalent dosing) and the inconsistencies in reports of Lithium Hypochlorite being able to dissolve (could be different brands so different granularity vs. powder).

By the way, the issues of some pools with waterfalls, etc. were pretty extreme aeration sources, not just a simple spillover. They were huge installations of water exposed to air. But I get your point that relative to pool water volume it's still pretty small. Nevertheless, lowering the TA generally worked for those cases and I understand that in a spa the aeration could be worse. However, spas are generally kept covered so that helps reduce outgassing since the air above the spa gets saturated with carbon dioxide so slows down further outgassing. I would expect a spa with a constant aeration source such as an ozonator to be even worse in pH rise if the cover was off all the time.

The numbers you gave would potentially start to see scale above around 8.1 in the heater as that is the saturation point at 104F so at the heater it's over-saturated. So for safety, a calcite saturation index of -0.2 is better and that would be at 7.9 so the pH should be kept below that for the CH and TA levels you are talking about. If the TA were lower, say at 50 (with a CYA of 20 since part of CYA is a component of TA), then the saturation point is closer to 8.3 in pH. The really difficult situations would be those people with high calcium hardness levels in their fill water. A water softener would probably be needed in such situations. You can use The Pool Calculator to calculate the Calcite Saturation Index (CSI) though this is a simplification of what is done in my spreadsheet so is off a little bit (but certainly less than all the measurement errors that can creep in). Note that TDS is important (that's what is shown as "salt", but is really TDS since putting in any number less than the theoretical TDS from calcium chloride plus sodium bicarbonate to produce the measured CH and TA just uses that theoretical amount). Normally, scale isn't seen in pools until the saturation index gets pretty high around +0.7 or higher, but that's scale visible on pool surfaces and no one is really looking at their heaters. It sounds to me like the -0.2 maximum target is much more important for spas due to the frequent use of gas heater compared to pools where that is far more infrequent.

I guess the way I look at it is that using Dichlor is in fact like adding a hypochlorite source of chlorine (bleach, chlorinating liquid, lithium hypochlorite) plus acid at the same time, but [EDIT] the Dichlor also adds [END-EDIT] CYA. I've just been trying to accommodate TinyBubbles desire for simplicity and not have to regularly add acid, but as waterbear has posted that's just part of what may be required.

There is unfortunately no free lunch here in that there isn't a single source of chlorine for spas that combines everything you need on a regular basis. If Dichlor didn't increase CYA, it would be really good as it's like having chlorine plus acid combined (when accounting for the acidity of chlorine usage). Over time, the TA would drop so some baking soda would also be needed, but not daily.

Richard

[Hillbilly Hot Tub]

you state that those pools with spillovers, fountains etc. that aerate the water have had issues. This is a very large body of water with what would be a small amount of aeration compared to a spa. Spas with multiple pumps, loads of jets, water falls and fans aerate the water much much more than a pool. Add this with hot water, bather/water ratio, maybe the spa and chemical industry is not full of it, maybe it is just to hard and to much work for the typical spa owner to get correct in their spa so why chance damageing equipment.

Also, I have 3 tubs I deal with, Nature 2 systems. Alk 80, CH 50 and when PH starts to rise (8.0-84), we start seeing scale forming. If left at the high PH to long it starts to stick to the jets and filter pretty bad, never mindwhat it does to the heater! I talked about this in another thread, we have lime in our well water in this area, along with many other minerals, although our calcium hardness is not high when we fill tubs. So what is causing the scale? Is there more chemistry involved that is being missed?

Just still trying to figure all this out....personal curiosity I guess!

I completely get your point and if it weren't for the fact that some people with spas are able to use the Dichlor then bleach approach without a serious pH rise then I'd just say you have to add acid as well as chlorine (not together in concentrated form, or course) to produce the same technical results as are accomplished with Dichlor, but without adding extra CYA. But maybe for some spa situations, that we have yet to precisely determine (i.e. ozonator vs. air in jets vs. jets themselves), if you use bleach then you need to use acid as well. There's also the apparent faster usage of bleach relative not only to Dichlor but also to Lithium Hypochlorite (though the latter could be non-equivalent dosing) and the inconsistencies in reports of Lithium Hypochlorite being able to dissolve (could be different brands so different granularity vs. powder).

By the way, the issues of some pools with waterfalls, etc. were pretty extreme aeration sources, not just a simple spillover. They were huge installations of water exposed to air. But I get your point that relative to pool water volume it's still pretty small. Nevertheless, lowering the TA generally worked for those cases and I understand that in a spa the aeration could be worse. However, spas are generally kept covered so that helps reduce outgassing since the air above the spa gets saturated with carbon dioxide so slows down further outgassing. I would expect a spa with a constant aeration source such as an ozonator to be even worse in pH rise if the cover was off all the time.

The numbers you gave would potentially start to see scale above around 8.2 in the heater as that is the saturation point at 104F so at the heater it's over-saturated. So for safety, a calcite saturation index of -0.2 is better and that would be at 8.0 so the pH should be kept below that for the CH and TA levels you are talking about. If the TA were lower, say at 50 (with a CYA of 20 since part of CYA is a component of TA), then the saturation point is closer to 8.4 in pH. The really hard situations would be those people with high calcium hardness levels in their fill water. A water softener would probably be needed in such situations.

I guess the way I look at it is that using Dichlor is in fact like adding a hypochlorite source of chlorine (bleach, chlorinating liquid, lithium hypochlorite) plus acid at the same time, but without adding CYA. I've just been trying to accommodate TinyBubbles desire for simplicity and not have to regularly add acid, but as waterbear has posted that's just part of what may be required.

There is unfortunately no free lunch here in that there isn't a single source of chlorine for spas that combines everything you need on a regular basis. If Dichlor didn't increase CYA, it would be really good as it's like having chlorine plus acid combined (when accounting for the acidity of chlorine usage). Over time, the TA would drop so some baking soda would also be needed, but not daily.

Richard

I am understanding more and more, but for the typical spa owner this is very difficult to compute. Thats why I said I think some of the spa manufactures say they will void the warrenty. Less chance for spa damage with di-chlor, they really don't care if you itch. This also goes with my statement about the manufactures are not trying to rip you off. I know you did not say that chem geek, but a lot of the bleach users have. As a dealer i try to do whats best for each customer. Makes for a long term relationship. It would also be nice if they could make di-chlor in a tablet form! I guess from what I am told, it exsplodes if they try to do that.

Thanks for the time you put into the posts.

[chem geek]

I am understanding more and more, but for the typical spa owner this is very difficult to compute. Thats why I said I think some of the spa manufactures say they will void the warrenty. Less chance for spa damage with di-chlor, they really don't care if you itch. This also goes with my statement about the manufactures are not trying to rip you off. I know you did not say that chem geek, but a lot of the bleach users have. As a dealer i try to do whats best for each customer. Makes for a long term relationship. It would also be nice if they could make di-chlor in a tablet form! I guess from what I am told, it exsplodes if they try to do that.

Thanks for the time you put into the posts.

Your welcome and thank you for keeping things real, so to speak. Take another look at my post as I updated it with a link to an online pool calculator you can use to help predict possible scale in the heater.

Though you may very well be right about why spa manufacturers just take the simple approach of saying to use Dichlor because it will help keep pH lower or more stable and won't over-chlorinate the water so makes the spa covers last longer compared to using ONLY bleach and it's a simpler message to just say "use this one thing", I cannot be so generous with the manufacturers of Trichlor for pools and what they've trained dealers to think that CYA is no problem (and they don't say that a cycle of algae then develops). It's not that they don't promote water care systems that include algaecides, but they don't say the real reason as to why a weekly dose of PolyQuat 60 is needed -- namely, that the buildup of CYA from Trichlor lowers chlorine effectiveness to the point that algae will develop (unless you correspondingly raise the FC level). It is not in the interest of a manufacturer to tell pool owners how to manage their pools using the least amount of basic inexpensive chemicals. I don't mind that part, but I don't like the attempts at saying "CYA doesn't matter; only FC matters" that I talk about in this thread about a study the industry uses to justify that stance even though the chemistry determined in 1973 plus numerous scientific papers since then say that it's the hypochlorous acid concentration that matters, not FC alone. And I also don't like the manufacturers influencing NSPI (now APSP) to publish guidelines that completely ignore the CYA/FC relationship and that say that CYA should not be used in indoor pools, etc. These recommendations aren't based on science, but on obfuscation of the CYA/FC relationship that the manufacturers do not want fully explored for whatever reason.

If this CYA/FC relationship didn't have consequences, then I wouldn't have spent any time on it, but it does have consequences and they may be more serious than anyone has imagined. It's one thing to have algae develop in pools since that's just unsightly and not a problem for health, but it's quite another to have no CYA in indoor pools such that they are over-chlorinated with the resultant much higher creation of disinfection by-products including nitrogen trichloride. At the other extreme, if too much CYA is used, then this results in a buildup of monochloramine. Both are irritating. At this point, it's all theory since I haven't gotten any indoor pool that doesn't use CYA to try and use it. Even indoor SWG pools that had serious corrosion of stainless steel weren't willing to just add some CYA to reduce that corrosion -- they just junked the SWG and replaced the water with lower salinity water instead. Some day, there will be some real data from real pools and when that day comes then maybe the industry will stop ignoring what the science says and just do what makes sense. It's been really frustrating for me -- and I'm just a pool owner!

Richard

[Hillbilly Hot Tub]

I am understanding more and more, but for the typical spa owner this is very difficult to compute. Thats why I said I think some of the spa manufactures say they will void the warrenty. Less chance for spa damage with di-chlor, they really don't care if you itch. This also goes with my statement about the manufactures are not trying to rip you off. I know you did not say that chem geek, but a lot of the bleach users have. As a dealer i try to do whats best for each customer. Makes for a long term relationship. It would also be nice if they could make di-chlor in a tablet form! I guess from what I am told, it exsplodes if they try to do that.

Thanks for the time you put into the posts.

Your welcome and thank you for keeping things real, so to speak. Take another look at my post as I updated it with a link to an online pool calculator you can use to help predict possible scale in the heater.

Though you may very well be right about why spa manufacturers just take the simple approach of saying to use Dichlor because it will help keep pH lower or more stable and won't over-chlorinate the water so makes the spa covers last longer compared to using ONLY bleach and it's a simpler message to just say "use this one thing", I cannot be so generous with the manufacturers of Trichlor for pools and what they've trained dealers to think that CYA is no problem since a cycle of algae then develops. It's not that they don't promote water care systems that include algaecides, but they don't say the real reason as to why a weekly dose of PolyQuat 60 is needed -- namely, that the buildup of CYA from Trichlor lowers chlorine effectiveness to the point that algae will develop (unless you correspondingly raise the FC level). It is not in the interest of a manufacturer to tell pool owners how to manage their pools using the least amount of basic inexpensive chemicals. I don't mind that part, but I don't like the attempts at saying "CYA doesn't matter; only FC matters" that I talk about in this thread about a study the industry uses to justify that stance even though the chemistry determined in 1973 plus numerous scientific papers since then say that it's the hypochlorous acid concentration that matters, not FC alone. And I also don't like the manufacturers influencing NSPI (now APSP) to publish guidelines that completely ignore the CYA/FC relationship and that say that CYA should not be used in indoor pools, etc. These recommendations aren't based on science, but on obfuscation of the CYA/FC relationship that the manufacturers do not want fully explored for whatever reason.

If this CYA/FC relationship didn't have consequences, then I wouldn't have spent any time on it, but it does have consequences and they may be more serious than anyone has imagined. It's one thing to have algae develop in pools since that's just unsightly and not a problem for health, but it's quite another to have no CYA in indoor pools such that they are over-chlorinated with the resultant much higher creation of disinfection by-products including nitrogen trichloride. At the other extreme, if too much CYA is used, then this results in a buildup of monochloramine. Both are irritating. At this point, it's all theory since I haven't gotten any indoor pool that doesn't use CYA to try and use it. Even indoor SWG pools that had serious corrosion of stainless steel weren't willing to just add some CYA to reduce that corrosion -- they just junked the SWG and replaced the water with lower salinity water instead. Some day, there will be some real data from real pools and when that day comes then maybe the industry will stop ignoring what the science says and just do what makes sense. It's been really frustrating for me -- and I'm just a pool owner!

Richard

I feel your pain, tough battle, we have gone through it on manufacturing issues too. I will say, thank god, I don't do pools! Just hot tubs and saunas(no water chemistry with saunas! ) to bad you can't go to some of these pool and spa shows where the cheical guys are there, and quite often the scientist that helped develop their particular chemical and talk face to face. The last show I went to the guy was try to tell me their MPS was 100% MPS, I asked quite plainly "no I mean the active potassium Peroxymonosulfate" and they swore it was 100% I just shook my head and walked away! Makes me wonder...

Your thoughts on chlorine resistant cryptosporidium...maybe needs to be another thread...

[greenworks]

I haven't been on here in a while what a read!

Just some more food for though on guys using bleach

Anyway I tested my Ph today and I am at 7.5 I use bleach and have used bleach for 4 weeks +or-. I have a tub that only cycles for 2-2 hour sessions and I make sure the air jets are off when I leave the tub based on not bringing cold air in to the tub to save on electricity. We also have the tub setup so my wife and I are in it during a cycling time (7-9pm). I have a 0 residual as well , I usually add 4-5 oz of 5% depending on the if the kids are in as well, I add 1-2 oz before to bring it up a little (1-2ppm) then when leaving the tub add the rest this will bring me up past 5 ppm then leave the cover off and the jets on low with no air for 10 minutes give or take. I assume that any problems that are brought in the tub will be killed therfore even though the fc is low after 7-8 hours it is fine due to anything that was there should have been oxidized.So the only time the jets have air is the 20-30 minutes during use, just though I would throw that in for info as well.

I should note I use a 1/8" foam water cover with another layer of open sided bubble wrap on top of it plus the tub cover, gets cold up here... must be working though as my first electric bill was $35 more than previous month and thats with a fill and heating from 51...

Jason

[chem geek]

Jason,

The only concern I have from what you wrote is that if you have zero residual then you may not be oxidizing all of the ammonia/urea that is in the water so over time it could build up and at some point you'd start measuring some CC. There should be a point where you up the dosage and a residual starts to appear at which point you can tune that to what you want. At least adding a little chlorine before you get in does kill bacteria rather quickly.

It sounds like you add a total of 5-7 fluid ounces of 5% bleach per day which in 350 gallons would be 6-8 ppm FC. That should be enough for around one person-hour of soaking so it sounds like the amount is on the edge of being right for you and your wife but is probably way too low when the kids are in. You can either increase the bleach amount or use some MPS to supplement. If soon after you add the chlorine before you get in you then test for CC and find some (unless you use MPS in which case you need an interference remover for the test), then that definitely means you aren't adding enough to keep up.

Do you have an ozonator? It sounds like you've got aeration minimized, but I don't recall if you have an ozonator. I also assume you initially used Dichlor -- do you know your CYA level?

Richard

[greenworks]

richard I do not have a ozonator, and the rates I use are a daily rate( usually 2 peopl 1/2hr) and I should mention once a week I use a quite high rate to get up over 10ppm as a shock. I wasn't really tring to hijack the thread only report that I am using bleach with no pH issues. Lastly I can't tell you any other water parameters as I ordered the tf-100 kit three weeks ago and haven't got it yet. I can report the levels once I recive it though.

The one thing that still troubles me is when I test for FC I see no results in a pink (taylor dual reactant) form yet 5-10 minutes later it reads 5 ppm, this is 24 hours after adding bleach.

[chem geek]

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.