CYA has crept up in the last 10 days.


Active member
May 21, 2017
Dracut MA
Hi Guys, I have a 12500 gallon OGP with sand filter. Outdoor temp has been about high 80's to low 90's.

These are my readings:
CH 10.8
PH 7.4
CH 270
ALK 80
CYA 60-65

The pool is not using hardly any chlorine. My reading 4 days ago was CH 12. I was using trichlor pucks and stopped about a week ago. The pool is crystal clear and has been all season (about 5-6 weeks). Should I just replace some water to get the CYA down as pool math has indicated or is CYA 60 ok? Thanks in advance.


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
I would suspect the trichlor pucks were still in the system. You may not have added any, but some were still dissolving and adding chlorine and CYA.
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