Should we lower CYA before closing pool?

[Diamonds1637]

Hey y’all,
Eastern PA, just bought a house with a plaster pool. Tested today for the first time. CYA is off the chart, estimating 120 but unsure. Should we try to balance the CYA before closing the pool? (Empty more water than we normally would and refill it a bit?)

Generally speaking, how balanced do you try to make your chemicals before closing?
See test results below:

Thanks so much in advance!
-Jess& Greg

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Test Results 10-08-2023 @ 10:28 AM
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Free Chlorine: 11.5
Combined Chlorine: 0.0
pH: 7.8
Total Alkalinity: 70
Calcium Hardness: 225
CYA: 120

 

[mas985]

Sometimes CYA drops after pool close due to either water overflow or other factors:

Degradation of Cyanuric Acid (CYA)

This thread explores some of the ways that Cyanuric Acid (CYA) can degrade since many users report seeing CYA drop under various conditions. CYA Degradation by Bacteria Some pool users find that their CYA levels drop over the winter when their pool is let go (i.e. no chlorine added). Many of...

www.troublefreepool.com

So I would wait until you open to make sure you still need to reduce it.

 

[Texas Splash]

I agree. If it were me, I would leave the CYA alone. Just increase the FC to about 30 and cover. Or give it a good duse of Polyquat 60 and close. Partial drain for winter closing and stabilizer degrading over the next few months and it should be good.

 

[mknauss]

When you open, if you test 0 CYA, please post here on the forum first before adding anything.