CYA dropped to 20


Well-known member
Apr 3, 2016
Baltimore MD
It's my least favorite test. It seems to have a mind of its own. Regardless, last week when I opened I was at CYA 30. Today I was at 20. I did it twice to double check.

Full results

pH - 8
FC - 5
CC - 0
CH - 325
TA- 70
CYA - 20
72 degrees with solar cover on.

Crystal TFP clear.

Last summer I was at CYA 30 pretty much the whole time but I seem to have dropped.

My question: From reading previous threads about using trichlor pucks I believe if each 3" puck adds 3 ppm of CYA in a 10,000 gallon pool then I will need about 9-10 pucks for my 27000 gallon pool to increase 10 ppm CYA (getting me to 30). I have never used a puck in my pool before so I have no idea how long it would take to get 10 pucks dissolved. Is that stupid? Should I just break out the CYA and the sock? I have a huge thing of pucks (that I bought prior to TFP) and would like to use them up.

Thoughts? Maybe one a week for a few a months on top of a sock addition?



Bronze Supporter
TFP Guide
Jul 24, 2015
Central Valley CA
You already bought them so might as well use them. What I would do is set aside 10 or 11 pucks load a bunch into a floater, adjust as needed to maintain an FC of around 3ppm. I have never used pucks either so I don't know how long it will take to use up all the pucks but look at it as vacation from having to manually add chlorine.


Silver Supporter
Jul 29, 2016
Back in the day when I used pucks, 5 pucks in the floater would last a bit longer than a week


TFP Expert
LifeTime Supporter
Jun 7, 2011
Midland TX
Thats OK John, people have a bit of a time with this test in the beginning, but just try not to second guess it. What you saw was sampling, testing, or lighting differences. Call it 20 and don't sweat it at all. It will get easier as you do it more.

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