Unstable PH


New member
Aug 12, 2015
I had to go through a SLAM process a few weeks ago to kiill algae and phosphates. Since then my PH has been unstable. My alkalinity is fine, my chlorine is fine for a day or two and the it disappears and my PH wil rise to 8.0. I have used Acid twice to get it down, which it does, but two days later it is right back up there. Thoughts?


TFP Expert
LifeTime Supporter
Jun 7, 2011
Midland TX
Hi Jennifer and welcome to TFP :wave:

So, a few things here. SLAM doesn't kill phosphates. Usually we don't address them because in almost every situation they are overcome by a reasonable amount of free Chlorine. When you say fine regarding the various parameters, can you please clarify that with the actual test results please? If you could post all your results and let us know how you obtained them, we can offer clear advice. Also, please clarify what you mean by unstable pH. In almost all pools, pH tends to rise, so what you briefly describe is pretty normal. Let us know about the above, and we can help.


TFP Expert
Feb 3, 2014
Central Minnesota
Posting some test results will help us help you. We don't really do advice based on "my levels are fine." If they were, then you wouldn't be here. What test kit are you using? How are you chlorinating the pool? Was it a proper SLAM with all criteria passed or was it simply a shock and pray? More details are needed to help you out.

Welcome to TFP! :wave:


Well-known member
May 22, 2010
Dexter, MI
What I found with my PH drift was that my pool likes the TA down around 60, once that happened I never had any PH drift, rock solid. So I guess what I'm saying is a fine TA # for my pool that keeps PH stable may not be appropriate in yours. My experience tells me that once the TA is right for your pool the PH will be stable.