Several of the comments say something like “the Pool Math recommendation to drain and refill is incorrect.” I agree with that, but why is the app not being corrected? For this reason and many others, I just can’t use Pool Math. I can’t trust it.
Can you help us out with more context, like what numbers are we talking about that lead to the recommendation?
Poolmath is spot on, but it is still just a tool.
The recommendation to drain and refill is given in pool math when your current CYA is higher that the target CYA that you enter. This is correct. Replacing water is the only way to reduce CYA (other than letting it degrade over time).
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