Problems keeping PH in check on indoor covered pool

I have an indoor pool. It's covered 90% of the time to retain the heat as we live in the high country of CO.
My problem is, my PH keeps creeping up over time (weeks). I get the Alkalinity correct and the PH correct and then over a few weeks, it's out of kilter again. I suspect it's due to the fact that the cover is on and it's not a breathable cover.

Looking for thoughts / suggests of others that may have had these issues.

Can you define "alkalinity correct and the pH correct"? What numbers are you targeting, and what are you using to achieve them? What do you use for chlorination?

Alkalinity is now 110 - is was 100 a few weeks ago. Not adding anymore water since getting pool balanced.
PH was 7.4 when balanced, now is off the scale at 8+
We use uv for keeping water sanitary.

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forgot to mention that i use muratic acid to get alkalinity correct. I used the aeration method of bringing up the PH once Alkalinity was correct - worked like a charm. I got the pool balanced and kept it balanced for about a week, not a heavy bather loader. then, it started creeping out of range on both PH and Alk. Alk is still ok at 110, but i can't figure out why PH keeps climbing up.

If you would, go ahead an fill out the pool chart form; it makes it a lot easier for us to answer questions like this:

Pool Chart Entry Form
Pool Chart Results

Include info on what chemicals you use in the notes section.

Quote:

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Originally Posted by blentz

We use uv for keeping water sanitary.

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I missed this in your post, but I noticed it in the chart. UV is *not* a sanitizer. It may kill things growing in the water; it will not kill pathogens in the pool . . . for the simple reason that the UV does not reach there.

If your water is not slimed AND you only swim with family members . . . you're reasonably safe. But regular use of polyquat (info):

Kem-Tek 60% polyquat @ Amazon
Nava 60% polyquat @ Amazon

will GREATLY increase your safety.

You can also use hydrogen peroxide as an oxidizer, with UV and polyquat:

Splashes H2O2 Shock

If you use both polyquat (3 ppm 2x per week) & peroxide (~50 ppm), you still won't be as safe as chlorine, but you will be much, much safer than you are now.