pH high : difficulty to define the next steps


Well-known member
Feb 10, 2020
NJ (shore)
I am about to close my pool. I had chlorine to the shock level to the pool three days ago with 3 gallons of chlorine.
I checked this morning the PH and it's very high, in the purple, and I have hard time to use the acid demand agent to get into the pink/red. It becomes blue and then turn yellow after 20 drops.
What should I do ?


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
It’s reading high because the pH test is not accurate when the chlorine is high. The acid demand test won’t be accurate either. So you either need to let the chlorine drop and retest when the FC is below 10ppm OR get a digital pH probe.


TFP Expert
LifeTime Supporter
Jun 12, 2009
NW Ohio
If you lowered your pH before bring the FC up then I wouldn't worry about it. Even if the pH is a bit higher than optimal it isn't a big concern in a vinyl lined pool.