High CYA at end of season


Active member
May 3, 2020
SW Michigan
Hi all,

We are in SW Michigan and we've got just a handful of swims left before we close up the pool.
We've made it through the Summer quite well with maintaining levels, but suddenly our levels are fluctuating (maybe due to cooler nights and sun higher in sky?), and I need some help navigating the next few weeks, please.

This mornings test results:
FC = 5.2ppm
CC = 0
pH = 7.4ppm
Total Alk = 40ppm
CYA = between 90-100

I know the CYA tests can be tricky, but assuming I did it right, do we really need to do a partial drain this close to end of season?

This will be our first winterizing which I am quite nervous about given the green/black muck we inherited from the previous owners this past March. We are really striving for a clean pool in Spring.

We purchased all the winterizing things already -- leaf net, non-porous cover, water pump for the cover, and chemical kit...
I wanted to avoid draining the pool down during winter if at all possible, so planned to deal with the skimmer accordingly. Does it now make more sense to drain the water down now or for winter given the CYA results?

Thank you!!