Lower PH during SLAM


New member
May 14, 2016
Kansas City / MO
I discovered Troublefree pools about three years ago. Thank you!!
Last week, I experienced a problem with my filter that required the sand to be replaced. Upon opening the filter, the sand was packed and dark brown. Two thirds of the sand was missing from the filter, its been about 6 years since it was last changed. Previously, my PH lingered at 7.8 prior to the sand filter problem. Had passed SLAM test in early June, but noticed the water was not crystal clear as in previous years. Hence investigation of a filtration problem with a professional. I lost a few days of pool circulation while the filter was diagnosed and repaired (removed old sand / replaced with new). While the pump was off, the pool began turning green due to the lack of circulation (Water temp is 85 degrees). I've restarted the SLAM a few days ago, but forgot to lower the PH first!! While the SLAM is in progress, I added Clorox PH lower (dry acid) to the pool, but the PH test shows its still 7.8. I'm hesitant to keep fiddling with lowering PH since its not reliable during the SLAM, but I'm concerned high PH might be damaging my pool and vinyl liner. Thoughts on how best to proceed? Thanks in advance.
FC 20
CYA 50
PH 7.8
TA 90
Water temp 85 degrees


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Welcome to the forum!
High pH will not harm anything. It can lead to calcium scale if your CH is high. You do not show that test.

In the future, do a deep clean of your sand filter each year. it sounds like it had clarifier and/or floc run through it.

If you ever have a situation where you cannot run the pump again, keep adding your liquid chlorine. Use a brush, broom, person, or sump pump to mix the water.

I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.
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