No cya when testing


Active member
Jun 6, 2018
Parkton NC
I had my cya at the correct level last year. I did not winterize the pool. When I tested cya using my Taylor kit, I’m showing no cya now. From reading the abc’s the only way I can reduce cya is drain and refill. So I’m lost.
Beginning in September, from hurricane Florence till a few weeks ago the rain never stopped and the pool was constantly overflowing out the skimmer. Is it possible with that much rain water it reduced my cya?


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Yes. Or at least it reduced it so low that it doesn't register. Depending on your view tube, that could be in the twenties! You can doublecheck if it's dilution by looking at how much the CH dropped, since rainwater has none. The percentages should be the close.

Also, CYA breaks down about 3% per month naturally. So if you lost half and then another 20% from natural breakdown, you could easily drop from 80 to below the test threshold.

Worst case, whatever bacteria it is got in there and turned the CYA into ammonia. Let's not go there yet, since it takes too much typing to explain.
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Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
CYA does degrade (and disappear) slowly, but overflowing rains can certainly do a number on your pool over time.

Folks in FL often have to monitor their chemistry levels when they get frequent rains.

Maddie :flower:
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Bronze Supporter
Jun 20, 2013
Northeast Arkansas
I always close the pool with CYA and open it with little to no CYA. Rain water displacement is a huge factor, especially this winter where we had a TON of rain. You could assume that you have some CYA that is just below the testable amount and add slowly. Maybe add enough to raise it 10 ppm at a time (sock in front of return method). That way you could test and make sure you aren't overshooting your target.
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