Water chemistry questions when closing a mesh-covered pool with polyquat

poolnewbie4

Active member
Sep 20, 2018
33
TN
I just found out that my pool service is coming to close our pool on Tuesday next week. Water temperature is 68 degrees, so it looks like I’m going to have to close with polyquat. I have never closed with the water this warm before so I have a few questions.
1. I just tested my water, and FC was 7.0, CC was .5, PH was 7.8, TA is 70, CYA appears to be around 20-30, calcium was 200. Phosphate level is probably high since pool is surrounded by trees that are dumping leaves into the pool constantly and I have no robot. I know that shocking the pool before closing is recommended, but I’m worried that if I get the pool up to shock level now, FC will be too high on Monday to add the polyquat. Would it do any good to just keep FC at slightly above half shock level for the next 4 days so it will be at half shock level on Monday when I add the polyquat? Or would I be better off shocking it because of my test results, even if it means that FC will probably be higher than half shock level on Monday?
2. Since CYA may only be 20-30 and I have a mesh cover that lets rainwater and a tiny bit of sunlight into the pool, could I use Dichlor to increase FC using pool math so I could Increase CYA at the same time? If so, what CYA level would be optimal when closing with a mesh cover? Last year, I think I closed with CYA of 50 and opened up to CYA of 20 so it kind of worries me to close with such a low CYA since I know that the rainwater over the winter will lower it.
3. Should I wait to decrease the PH until the day before closing when I add the polyquat?
 

Texas Splash

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Would it do any good to just keep FC at slightly above half shock level for the next 4 days so it will be at half shock level on Monday when I add the polyquat? Or would I be better off shocking it because of my test results, even if it means that FC will probably be higher than half shock level on Monday?
With such a low CYA, you're pretty close to SLAM level now anyways, so I would just take it up to 10 - 12 now, give the pool smoe good brushings, and by next Tuesday teh FC should be fine.

could I use Dichlor to increase FC using pool math so I could Increase CYA at the same time? If so, what CYA level would be optimal when closing with a mesh cover?
Yes, and I thing around 40 - 50 would be better.

Should I wait to decrease the PH until the day before closing when I add the polyquat?
Sure
 
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Bperry

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Aug 20, 2020
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For reference, I’m also in TN and haven’t had a need for polyquat. I just increase it to SLAM level and put the mesh cover on and open up to a clear pool when March rolls around. But my water is 62F right now.
 
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