Conquering CYA


Jul 3, 2018
San Antonio /Texas
I have constant high CYA even after draining 1/2 of pool in early March and another 12 inches of water replacement.

CYA ranges from 100 to 70.

Got PH down from 8.0+ to 7.0 with MAcid
Slammed due to some algae.
FC is 14 day after slamming.
TA is 70.
Working on balance.

Even when pool is mostly balanced, CYA stays high. I recently stopped using trichlor and back to liquid bleach. Is there anything else I can do besides draining .....again.


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
You know the drill ...

Stop using trichlor and shock and and any solid chlorine. They all contain CYA or calcium.

Drain your water until your CYA is below 50.

Note that pH tests are unreliable when FC is above 10. So once you start a SLAM just test FC and CC until FC below 10.
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