Alkalinity Level with Auto Pool Cover

faby3003

LifeTime Supporter
Jul 14, 2011
244
St. Paul, MN
For those of you with auto pool covers where your pool is covered the majority of the time, what TA level do you find you need to keep pH stable? Before my auto cover, a TA of 90 would give stable pH. With the auto cover, I find I need my TA to be 120-130. I understand that with the cover on there is less CO2 outgassing. Just curious if others have observed the same phenomenon.
 

santacruzpool

Gold Supporter
Feb 24, 2015
561
Santa Cruz, CA
My TA is always about 90 - it hasn't moved much no matter what I do. Our fill water is high TA (150 I think?), and we only have 2 therapy jets on one wall that could help us lower the TA...

I end up putting in around 16oz of Kemtek 14.5% acid each week, so haven't tried to lower the TA to say 70...
 

dfahrion

Bronze Supporter
Oct 18, 2013
89
Iowa
When just using bleach our manually chlorinated auto-covered pool seems to be pH stable regardless of TA level. I've had it as low as 90, and currently it is at 200 (It's been a crazy opening this year). When we first moved in I was letting the TA drift down to TFP recommended range, but then before we went on vacation I added trichlor pucks to the feeder to see how that worked and was surprised to see my pH drop like a rock. Since then I keep the TA higher in the 120-140 range since we don't ever seem to have any pH drift, which I understand is the only reason to keep it low.

In 3 years, I've only once added acid, and that was when we first moved in after replacing 3/4 of the water to lower CYA. With the exception of this spring opening, I only add soda ash when using trichlor, by keeping the TA higher I don't have to add soda ash as often when using it.
 

faby3003

LifeTime Supporter
Jul 14, 2011
244
St. Paul, MN
When just using bleach our manually chlorinated auto-covered pool seems to be pH stable regardless of TA level.
That seems to be somewhat similar to what I am experiencing. When my TA is around 90, my pH wants to be stable at 7.2-7.3. If I add borax to get it to 7.6, it will slowly drift back down to 7.3.

This year my TA is around 130 (because I had to add some tap water this spring) and my pH is holding steady closer to 7.5.
 

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