pH drift, what is "normal" ?


Gold Supporter
May 27, 2019
Houston, TX
I've been using Cal-Hypo 73% for Chlorine, as I needed to raise CH. I just reached 350 CH, so switching over to 10% bleach.

pH has been drifting a little. I'll start it at 7.7. Over about 3 days, it will reach 7.9, at which point I put in about a quart of HCl, taking it back to 7.7. TA had been about 70, but is down to 60. Borates are right around 30. I ran out of Borax and the Boric acid arrived but I haven't put it in yet...

My backyard has only low fruit trees and a nearly constant breeze. Someone mentioned this might be driving the TA/carbonates down with CO2 loss and affecting pH.

I'm contemplating adding some baking soda to get back up. Will this help with the pH drift? Is this pH drift relatively normal?

My acid use is "minimal", maybe a gallon every 2 weeks.


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
With borates you should not be adjusting things until needed. The Cal Hypo pushes the pH up too. The acid you have added consumes the TA.

Do not add acid or baking soda. Now you are done with the cal hypo, see how things balance.