PH Rate of Rise

Billtkat

Well-known member
Apr 25, 2020
94
Oro Valley, AZ
What would be considered an average rise in PH for a plaster , outdoor pool ? I have seem mention if PH rises to fast might want to adjust TA in pool. I think it was increase TA however correct me if I am wrong - Just made me wonder as my CYA & CH seem to stay locked in and my nightly routine of bleach is 32 oz. What seems to move is my PH and I add acid to 7.5 and over the week it climbs to 8 , then back I add acid to go back to 7..5 My last TA reading was 60 however going to check at some point today
thanks
 

kevinskii

Gold Supporter
Aug 6, 2019
96
Los Angeles, CA
I can't tell you whether this is normal, but I can give you a point of reference. My TA is steady at 100. My pH rises about 0.1/day. I add a few ounces of muriatic acid almost every day to keep it at 7.6. My pool and spa are about 18k gallons. As for aeration, the spa jets are run for a few minutes every day and the bather load is fairly light.
 
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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Bill, there is no one perfect or standardized answer for pH rise. In general, we all would like for the pH to find a place to sit and stay so that we don't have to add acid very often. Pools of all types vary. Some settle at about 7.5-7.6 while others are almost always at 7.8. Your equipment, amount of swimming, aeration from other items like a waterfall or spill-over also contribute to pH rise. Yes, if the TA is elevated it can allow the pH to rise as well. You didn't post your TA, but if it was say 100 for example, and the pH was rising quickly every 2-3 days, you could lower the TA down to 80, then 70, and maybe 60. That might help slow the rise of pH. I usually have to add about 1-2 cups of acid per week in my pool, some others more while others less. Just depends. But as you control the pH in the 7.6-7.8 range, the TA should eventually settle as well so that they both find that "sweet spot" that is consistent.

ABCs of Pool Water Chemistry
 

Billtkat

Well-known member
Apr 25, 2020
94
Oro Valley, AZ
Bill, there is no one perfect or standardized answer for pH rise. In general, we all would like for the pH to find a place to sit and stay so that we don't have to add acid very often. Pools of all types vary. Some settle at about 7.5-7.6 while others are almost always at 7.8. Your equipment, amount of swimming, aeration from other items like a waterfall or spill-over also contribute to pH rise. Yes, if the TA is elevated it can allow the pH to rise as well. You didn't post your TA, but if it was say 100 for example, and the pH was rising quickly every 2-3 days, you could lower the TA down to 80, then 70, and maybe 60. That might help slow the rise of pH. I usually have to add about 1-2 cups of acid per week in my pool, some others more while others less. Just depends. But as you control the pH in the 7.6-7.8 range, the TA should eventually settle as well so that they both find that "sweet spot" that is consistent.

ABCs of Pool Water Chemistry
Thanks - Just tested and TA is 70 and PH was 7.8. All ok in range however PH was 7.5 on Sat and just wondered how long it should stick. Sounds like not raising my TA is the right direction and using acid if I hit 8.0 on PH would be how to address it - Or should I add a little acid each night to keep the 7.5 ?
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
I would just take it easy and stay the course with adding a little acid every 3 days or so but not each night. Let the pH get to 8.0 then lower it to about 7.5 or so. No need to go too low. The TA will slowly drop just a little more anyway. Ober time, it's okay to let the TA fall to 60, maybe even 50 is needed. But if later the TA goes below 50, bring it back up.
 
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