Cold Water Effect Shock Value?


Mod Squad
TFP Expert
LifeTime Supporter
Apr 17, 2010
East Texas
I certainly understand that when we're all in our happy summer mode pool zone and the weather is warm, that the relationship between CYA level and shock level is a given.

But when the water temps drop from 92ish down to 70---------60----------50 or lower, does that relationship still hold?
Does a given CYA level require the same shock levels regardless of temperature of the water? I know just the normal daily CL usage drops significantly.


chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
Hopefully you won't have to shock your pool when it gets cold because you won't be getting any algae, but if for some reason you do need to then yes the same chart and relationships are used. It will be slower to clear a pool of algae when it's cold because all chemical reactions slow down -- both algae growth rates and chlorine kill/oxidation rates.

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