Ph keeps rising, other parameters okay

[FernTheBrute]

Above ground vinyl liner pool. Tested at the pool store.

Alkalinity around 95
Calcium at 200
Cya at 40
I use a variable amount of liquid chlorine daily to keep its level at 3-4, depending on sun, heat and usage.

Somehow, my Ph keeps rising to around 8. I've been adding Ph- almost daily, which brings the water back to a better 7.4-7.6, but a day later it's back.

Any clue on where to start?

 

[mknauss]

pH rises if the TA is high. Keep pH in the 7's and the TA will fall. When it gets to 50 ppm or so, the pH will not rise as fast.

You need to get a proper test kit and test your own chemistry.