How to calculate how much CYA in a puck


Well-known member
Jul 21, 2018
Richmond, TX
I know this question has been asked before, and I have read the answer, but I can't find it right now. I am kicking myself. I left the water on overnight and did an unintended water exchange. I measured this morning and my CYA had dropped so I could see the dot with a full tube, so I am calling it 30. I have a bucket full of leftover pucks, and I would prefer to raise my CYA by using up my pucks. How do I calculate how many pucks I need to raise my CYA? I have an inline chlorinator so I can just put the pucks in there. My pool and spa together are 21,250 gallons. Someone mentioned using the pool math app to figure this out but it was not obvious to me how to do that. Sorry for asking a question that I know has been answered many times. :(


TFP Expert
LifeTime Supporter
Jul 21, 2011
Eastern Ohio
Pool Size
Liquid Chlorine
As Marty said, use the effects of adding under the “Hamburger menu.” You’ll then select Trichlor and enter the weight of the tab, likely 8 ounces.
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