Water added, CYA reduced?


Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
Franklin, NC
When I opened my pool I added about 18" of water to it. I guess that's not enough to drop my cya.
The answer is, it depends.....

Where did the water go that you replaced? If you pumped it out in the fall for winterization, then yes - your CYA did go down. HBow much only testing will determine.

But, if water is replaced because of evaporation then no, the CYA does not go down. When water evaporates it leaved behind the "stuff" in the water and only pure water goes away. Evaporation does not help with reductions of things like CYA, Iron, Copper or CH (calcium).