Accidentally added pH Up instead of down.
- Thread starter christianday
- Start date
Hi Chem Geek,
My FC is only 5.5 and the CC is 0 so it's not the chlorine. I always take the water from 18" out and 18" down with my finger over the top so none of the top level water gets into the sample as I take the vial out of the pool.
Here's the other kicker. It took a gallon and a half of MA to bring the pH down from where it was last night to what roughly appears to be 7.3 to 7.4 so it takes far more MA with the borates in there to lower the pH but with the swim jets running for about ten to fifteen hours total during the past eight days before the most recent test to spike that pH AND the TA. I read in several places that aeration wasn't supposed to raise so I still am completely confused about the TA/pH relationship.
If the harsh reality of this is that I have to add two gallons of muriatic acid per week to swim, I'm hiring someone to put in the chemicals each week, though I may want to look into one of those measured dispensers of muriatic acid that adds it over time at a percentage rate, NOT via a sensor since I won't ever trust that. Anyone familiar with the compatibility of these things? Will they work with Hayward?
My FC is only 5.5 and the CC is 0 so it's not the chlorine. I always take the water from 18" out and 18" down with my finger over the top so none of the top level water gets into the sample as I take the vial out of the pool.
Here's the other kicker. It took a gallon and a half of MA to bring the pH down from where it was last night to what roughly appears to be 7.3 to 7.4 so it takes far more MA with the borates in there to lower the pH but with the swim jets running for about ten to fifteen hours total during the past eight days before the most recent test to spike that pH AND the TA. I read in several places that aeration wasn't supposed to raise so I still am completely confused about the TA/pH relationship.
If the harsh reality of this is that I have to add two gallons of muriatic acid per week to swim, I'm hiring someone to put in the chemicals each week, though I may want to look into one of those measured dispensers of muriatic acid that adds it over time at a percentage rate, NOT via a sensor since I won't ever trust that. Anyone familiar with the compatibility of these things? Will they work with Hayward?
I also want to point out that your pool is relatively new so plaster curing also has the pH rise and you also have a saltwater chlorine generator and that also contributes to a rise especially if the generator is fairly close to the pool (i.e. short pipe run) since chlorine gas can be outgas before it fully dissolves.
For curing plaster, if it results in 10 ppm CH increase from calcium hydroxide, then that raises the TA by 10 ppm and the pH can go from 7.5 to 8.4 without borates or to 7.8 with borates (so you see how normally the borates would help). If your CH went up 50 ppm from this, then the TA would go up by 50 ppm but the pH would go to 10.1 with no borates or 8.5 with borates. Without the borates, if the pH really went up that high, then I would have expected to see scaling or cloudiness from plaster dust. So some of these movements for CH and TA aren't making much sense. Even for evaporation and refill, to go from 350 to 450 ppm you'd need a huge amount of your water evaporated and refilled (nearly all of it). So if you are really seeing CH shoot up very high as you are, then it does seem like maybe the main source of the problem is the plaster that for whatever reason did not settle down in curing as it should in the first days.
What is most strange in your situation is how the TA is jumping around hugely (especially going down without acid addition or water replacement -- that simply does not happen). That just doesn't make any sense. It does go up and down with pH from acidic and basic sources, but not as much as you are seeing and as I noted seeing such large increases in CH is also not good.
For curing plaster, if it results in 10 ppm CH increase from calcium hydroxide, then that raises the TA by 10 ppm and the pH can go from 7.5 to 8.4 without borates or to 7.8 with borates (so you see how normally the borates would help). If your CH went up 50 ppm from this, then the TA would go up by 50 ppm but the pH would go to 10.1 with no borates or 8.5 with borates. Without the borates, if the pH really went up that high, then I would have expected to see scaling or cloudiness from plaster dust. So some of these movements for CH and TA aren't making much sense. Even for evaporation and refill, to go from 350 to 450 ppm you'd need a huge amount of your water evaporated and refilled (nearly all of it). So if you are really seeing CH shoot up very high as you are, then it does seem like maybe the main source of the problem is the plaster that for whatever reason did not settle down in curing as it should in the first days.
What is most strange in your situation is how the TA is jumping around hugely (especially going down without acid addition or water replacement -- that simply does not happen). That just doesn't make any sense. It does go up and down with pH from acidic and basic sources, but not as much as you are seeing and as I noted seeing such large increases in CH is also not good.
Just read your latest post. So you DO need to add more acid to move the pH now that the borates are there but that is not a bad thing because it means that without the borates the pH would have been even higher. The amount of acid you need to add over time, however, shouldn't change with the borates unless they are causing a problem with greater evaporation and refill from the lower surface tension, but it doesn't sound like that's the case.
So at least when the swim jets are off, the issue may be the plaster and that hopefully will settle down over time. That would also explain at least some of the rise in TA because calcium hydroxide getting into the water increases CH, pH, AND TA. The CH and TA should rise the same amount, however, and you are seeing the TA rise more. That part doesn't make sense. Also, the amount of CH rise you have been seeing is way more than one should see from plaster and ideally one wants enough TA in the water that there is no CH rise and instead the plaster converts calcium hydroxide to calcium carbonate in place. Not good that this isn't happening that way.
The other possible source for a pH AND TA rise is undissolved chlorine gas outgassing. Is it possible for you to point the return that is closest to the SWCG downward (or diagonally downward) to give the chlorine gas bubbles more of a chance to dissolve in the water? Yet another possibility is that hypochlorous acid itself is getting outgassed from all the aeration. That also raises pH and TA, but only half as much as undissolved chlorine gas.
So there ARE possible sources of TA rise: plaster curing (calcium hydroxide), outgassing of undissolved chlorine gas from a short pipe run, and hypochlorous outgassing. It's only carbon dioxide outgassing that results in a rise in pH with no change in TA. So to sum up, let me outline below each of these effects and how much full-strength acid is needed to compensate for the pH change and what the resulting TA would be after such acid addition (this is all in 10,000 gallons) and I start with a pH of 7.5 and TA is 60 ppm.
Source of pH rise ..... CH .... pH .... TA ... Acid To Compensate for pH . TA result after acid addition
Plaster Curing ........... +10 ... 8.7 ... +10 ... 25.5 fluid ounces ................... TA back to where it was
Bicarb Startup ............ +0 .... 8.0 .... +0 ... 12 fluid ounces ...................... TA reduced by 4.7 ppm
5 ppm Cl2 outgas ........ +0 .... 8.3 .... +7 ... 18 fluid ounces ...................... TA back to where it was
5 ppm HOCl outgas ..... +0 .... 7.8 .. +3.5 .... 9 fluid ounces ...................... TA back to where it was
10% of CO2 outgas ...... +0 .... 7.9 .... +0 ... 10 fluid ounces ...................... TA reduced by 3.9 ppm
Evap. and Refill ............ + ....... ? ..... + ....... ?
If the pool builder has the swim jets in the same circulation loop as the SWCG, then that is terrible and could be part of the problem. To see if this is the case, turn off the SWCG when the swim jets are on. That may not completely stop the rise, but if it helps then that is at least a part of the problem (the chlorine gas outgassing part of the problem). The "Bicarb Startup" is not what you have but what would be a better way of the plaster curing where the calcium is kept within the plaster.
So at least when the swim jets are off, the issue may be the plaster and that hopefully will settle down over time. That would also explain at least some of the rise in TA because calcium hydroxide getting into the water increases CH, pH, AND TA. The CH and TA should rise the same amount, however, and you are seeing the TA rise more. That part doesn't make sense. Also, the amount of CH rise you have been seeing is way more than one should see from plaster and ideally one wants enough TA in the water that there is no CH rise and instead the plaster converts calcium hydroxide to calcium carbonate in place. Not good that this isn't happening that way.
The other possible source for a pH AND TA rise is undissolved chlorine gas outgassing. Is it possible for you to point the return that is closest to the SWCG downward (or diagonally downward) to give the chlorine gas bubbles more of a chance to dissolve in the water? Yet another possibility is that hypochlorous acid itself is getting outgassed from all the aeration. That also raises pH and TA, but only half as much as undissolved chlorine gas.
So there ARE possible sources of TA rise: plaster curing (calcium hydroxide), outgassing of undissolved chlorine gas from a short pipe run, and hypochlorous outgassing. It's only carbon dioxide outgassing that results in a rise in pH with no change in TA. So to sum up, let me outline below each of these effects and how much full-strength acid is needed to compensate for the pH change and what the resulting TA would be after such acid addition (this is all in 10,000 gallons) and I start with a pH of 7.5 and TA is 60 ppm.
Source of pH rise ..... CH .... pH .... TA ... Acid To Compensate for pH . TA result after acid addition
Plaster Curing ........... +10 ... 8.7 ... +10 ... 25.5 fluid ounces ................... TA back to where it was
Bicarb Startup ............ +0 .... 8.0 .... +0 ... 12 fluid ounces ...................... TA reduced by 4.7 ppm
5 ppm Cl2 outgas ........ +0 .... 8.3 .... +7 ... 18 fluid ounces ...................... TA back to where it was
5 ppm HOCl outgas ..... +0 .... 7.8 .. +3.5 .... 9 fluid ounces ...................... TA back to where it was
10% of CO2 outgas ...... +0 .... 7.9 .... +0 ... 10 fluid ounces ...................... TA reduced by 3.9 ppm
Evap. and Refill ............ + ....... ? ..... + ....... ?
If the pool builder has the swim jets in the same circulation loop as the SWCG, then that is terrible and could be part of the problem. To see if this is the case, turn off the SWCG when the swim jets are on. That may not completely stop the rise, but if it helps then that is at least a part of the problem (the chlorine gas outgassing part of the problem). The "Bicarb Startup" is not what you have but what would be a better way of the plaster curing where the calcium is kept within the plaster.
I'm not sure I believe anymore that the pH would have been higher. It never, ever spiked that high in an eight-day period before I added the boric acid. I get what all the data says but something's up. Maybe my pool is possessed. LOL
Who knows if it's plaster rising the CH but as soon as we've had the plaster a year, I'm going to have the pool filled with distilled water and add exactly what chemicals are needed.
Who knows if it's plaster rising the CH but as soon as we've had the plaster a year, I'm going to have the pool filled with distilled water and add exactly what chemicals are needed.
Well the borates do help prevent the pH from rising as much in the SWCG so help prevent scaling there, but you are right that if they have some negative side effect with the swim jets to make outgassing worse (so more pH and possibly TA rise from that), then that's not good.
So basically, I have to get rid of the borates completely. Because, if I do not, and if I have a pool chemical company come weekly, the pH will spike too often between the times they are here. I wish I had known that because everything I had read said that borates were actually good for holding pH steady against water features. Clearly, they are not. My pH and TA never raised so high so fast as when I added borates.
Well I didn't know that either because in all other pools adding borates has the pH rise more slowly or worst case doesn't change the apparent rate very much. We've never seen it make the pH rise worse, but your situation is the only swim jet situation we have seen as far as I recall. I'm sorry you are having problems with this and that the borates made it worse.
The borates are most definitely an additional pH buffer and more strongly buffer as the pH rises. That's a chemical fact. In your pool there must be some other factor about borates that makes your problem worse and the only think I can think of is that it reduces surface tension of the water so if you have a lot of aeration it could make that worse. There is probably some cross-over point where it helps until there is some amount of aeration above which it is worse. That would explain why most with waterfalls and spillovers don't see a problem with borates but you do.
[EDIT]
I should also note that borates are used in spas with the Dichlor-then-bleach method and spas have aeration jets and the pH is controlled well when the TA is low and borates are used. So there is something unique with your situation that we haven't yet figured out. Though the swim jets may be a contributing factor, there's something else also going on and since you find that adding acid over time to control pH isn't lowering the TA much over time, that means the source of pH rise isn't carbon dioxide outgassing.
I searched for "swim jets" on this forum and found four threads, but they did not refer to either rising pH (or TA or CH) nor borates.
Since you are adding a lot of acid to your pool, you should be extra careful to add it slowly over a return flow with the pump running and to lightly brush the side and bottom of the pool where you add the acid to ensure thorough mixing. Your pool is plaster and can be damaged by concentrated acid if it pools at the bottom.
Also, if your builder has made other swim jet pools especially with plaster surfaces and using an SWG, then ask him how he suggests handling the pH rise in those pools.
[END-EDIT]
The borates are most definitely an additional pH buffer and more strongly buffer as the pH rises. That's a chemical fact. In your pool there must be some other factor about borates that makes your problem worse and the only think I can think of is that it reduces surface tension of the water so if you have a lot of aeration it could make that worse. There is probably some cross-over point where it helps until there is some amount of aeration above which it is worse. That would explain why most with waterfalls and spillovers don't see a problem with borates but you do.
[EDIT]
I should also note that borates are used in spas with the Dichlor-then-bleach method and spas have aeration jets and the pH is controlled well when the TA is low and borates are used. So there is something unique with your situation that we haven't yet figured out. Though the swim jets may be a contributing factor, there's something else also going on and since you find that adding acid over time to control pH isn't lowering the TA much over time, that means the source of pH rise isn't carbon dioxide outgassing.
I searched for "swim jets" on this forum and found four threads, but they did not refer to either rising pH (or TA or CH) nor borates.
Since you are adding a lot of acid to your pool, you should be extra careful to add it slowly over a return flow with the pump running and to lightly brush the side and bottom of the pool where you add the acid to ensure thorough mixing. Your pool is plaster and can be damaged by concentrated acid if it pools at the bottom.
Also, if your builder has made other swim jet pools especially with plaster surfaces and using an SWG, then ask him how he suggests handling the pH rise in those pools.
[END-EDIT]
My pool builder custom engineered these swim jets from standard aerated pumps and it was a first time for them. They work probably better than anything out there, probably even Endless Pools, but their affect on the pool is clearly something we never anticipated. They not only change the surface of the water, the entire pool looks like a flowing river with all four of these jets on. So no, the pool builder doesn't know. I am asking him to look into the Sense and Dispense though. I'm terrified of anything adding the wrong amount of pH to the water and don't want to have to check the pH every day but if I can set a max on how much it can add in a day, it should be fine. Not even sure if Sense and Dispense works with the OmniLogic panel but I guess we'll see.
I created a new thread since I want to get more folks looking at this if we can. I doubt many are as chemically savvy as you but some input might set us in the right direction.
Crazy ph
I created a new thread since I want to get more folks looking at this if we can. I doubt many are as chemically savvy as you but some input might set us in the right direction.
Crazy ph
PAGirl, there's definitely less of a rise without the jets but there's still a rise. The filter is on more though (though no more chlorination than normal.