Lowering TA question.

mcinlb

Active member
Aug 24, 2017
44
Long Beach, CA
Our pool pH keeps rising to about 8.2-8.4. I am now going through the cycle of adding acid to drop the pH to 7.2-7.3 and letting it go back up naturally. This morning, with the pool @ pH 8.4, I added ~ 110fl oz of 14.5% muriatic acid. This dropped the pH to about 7.3. TA is currently at 90. Was curious how many cycles of this I'd need to run through to get the TA down to about 60?

Thank you!
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,654
Tucson, AZ
It is recommended that you let your pH rise to 7.8 and then knock it down to 7.2. When you do that, the amount of acid needed typically reduces the TA by 10ppm each time. So it should only take a few cycles to do that. One problem though is that the time it takes for the pH to rise usually gets longer as the TA gets lower. If you have high TA fill water and enough evaporation, you can reach a point where you are fighting against your fill water causing the TA to climb back up. So we typically recommend strongly aerating your pool to force the pH to rise faster so you can speed up the process.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,059
San Dimas, CA (LA County)
Our pool pH keeps rising to about 8.2-8.4. I am now going through the cycle of adding acid to drop the pH to 7.2-7.3 and letting it go back up naturally. This morning, with the pool @ pH 8.4, I added ~ 110fl oz of 14.5% muriatic acid. This dropped the pH to about 7.3. TA is currently at 90. Was curious how many cycles of this I'd need to run through to get the TA down to about 60?

Thank you!
Go to PoolMath and plug in your numbvers. Then go down below the table to Effects Of Adding Chemicals and see what adding your dose of acid will do to the TA. Ignore the pH-- it's only right within very narrow parameters. Just look at TA. As the TA goes down, the amount of acid needed to effect a pH change also goes down, so the TA reduction also slows. But it should give you some idea of the progress you're making. When you get to where it's only going to be -6 and you're adding water, it may take 3 or 4 cycles to do enough to register on the TA test! But it's dropping.
 
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mcinlb

Active member
Aug 24, 2017
44
Long Beach, CA
It is recommended that you let your pH rise to 7.8 and then knock it down to 7.2. When you do that, the amount of acid needed typically reduces the TA by 10ppm each time. So it should only take a few cycles to do that. One problem though is that the time it takes for the pH to rise usually gets longer as the TA gets lower. If you have high TA fill water and enough evaporation, you can reach a point where you are fighting against your fill water causing the TA to climb back up. So we typically recommend strongly aerating your pool to force the pH to rise faster so you can speed up the process.
Thank you. The pool has a spillover from spa that is running constantly, so aeration shouldn't be an issue. We also have a waterfall (that is normally off) that I could run to aerate even more. I'll check the pH this afternoon to get an idea of how much the spa spillover is increasing the pH.
 

CarolineM

Silver Supporter
Jun 20, 2018
219
Annapolis, MD
Your spill over running constantly is causing your PH to rise so quickly. That is good for wanting to lower your TA, but once your TA is lowered you will still be dealing with your rising PH from the spill over.