CYA level high….when to drain?


Jun 14, 2021
Oklahoma City, OK
Pool Size
Liquid Chlorine
TC: 5
FC: 0
PH: 7.6
TA: 60
CH: 550
CYA: 70

Testing results have been very consistent all season. With Calcium and CYA levels at the high end. I’ve been adding muriatic acid a few times a week to keep pH from creeping up and prevent scaling (about 10oz every other day or so)

Liquid chlorine only, so the CYA stayed right at the high end all season, as well.

My question: here in OK we don’t really close pools or use covers. Just run limited pumps all season and use freeze protection during the few days a year that it gets below 32.

Should I drain halfway and refill now? Or wait until the beginning of the summer? Is there any advantage to one of those?



Gold Supporter
Jun 28, 2017
Fresno, CA
Pool Size
If you can expect significant rainfall in your area then you can time partial drains and dilutions. 70 ppm CYA is not an emergency especially in the winter with colder water temps and less algae pressure. You may want to check the ppm again early next spring and make your final drain and dilution. Or you could install a SWCG system now it works well at a 70 ppm CYA.


Bronze Supporter
Jul 10, 2018
Las Vegas, NV
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
By next spring, I would assume, your cya could be down to 50 ppm or so. Let it go till then. You can test as the water gets warmer and determine if you want to tackle your CH and CYA at that point in time.
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