CYA Usage


Well-known member
Sep 9, 2018
Summit Hill, PA
My CYA went from 70 to 50 after several rain storms. Is it normal to have to add CYA during the season? Pardon me for the silly question but this is the first year with a pool and up to now my numbers have been pretty good according to TFP standards.


Well-known member
Jun 16, 2019
Pardon me for the silly question
The only silly question is the one you don’t ask. We are here for a reason and that’s to help.

Yes it’s completely normal to need a mid season top off of CYA. Some gets diluted due to rain or refilling from evap/ splash out and also it degrades on its own 2-5 units a month. A loss of 5 is not noticeable at 67 because 62 still round up to 70, But at 62 the loss becomes 57 and rounded up to 60 so that could be noticeable in FC loss this time of year with the highest FC demand. Your findings of being low by 20 would likely be even more noticeable.
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