This season my pH has been low and I've been unable to bring it up. Pool Calc says I need 1-2 boxes of borax. However I have already added 4 boxes of Borax in the past month with no longterm effect. The highest pH reading I've seen is 7.2, but it slips back down after about a week. Do I keep dumping in borax or should I do something different?
I have a 12,000 gallon fiberglass pool with a sand filter, gas heater, automatic cover, and Baracuda G3 in Indiana. I use bleach for opening or big changes, trichlor for ongoing maintenance (primary), and dichlor powder (rarely). I've used baking soda and muriatic as needed. I've never used pool store PH UP or PH DOWN products or anything exotic.
We have had a ton of rain this spring, but the pool is always covered. I don't think significant rain is getting in the pool.
This is my third season and it's been remarkably trouble-free. Almost all I have done is add chlorine and it's been extremely stable. The water has always been crystal clear.
Using a Taylor DPD kit
CYA 70 (one month old pool store measurement)