Lower pH or leave alone?

JPMorgan

Well-known member
May 22, 2018
400
Elmhurst, IL
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
I will close my pool on Sunday for the season. Recent tests show all levels within appropriate ranges. With pH of 7.8 and water temp of 55, I get a CSI of -.17. As water temp drops, Pool Math shows that CSI also drops. If I lower pH to 7.6, CSI drops even more. Should I just leave the pH where it's at and proceed with closing? Also.... what's the lowest water temp I should enter in Pool Math to get an accurate CSI for the winter months?
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,893
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
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Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
As the water temps falls, the pH will rise. To some degree they help to counter-balance each other. TFP closing instructions state to lower pH to about 7.4 - 7.6 at closing which allows a bit of time for later when the water temps really crash, but allows for the pH to rise. As for a water temp in Poolmath, you might enter an average water temp are for your area based on the next 4 - 5 months.
 

JPMorgan

Well-known member
May 22, 2018
400
Elmhurst, IL
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
Thanks, Splash. I realized that I asked this same question on the Forum about this time last year... but I appreciate the "refresher". Dropped the pH down a little bit today. Should be good to go for closing on Sunday.
 
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