Problems keeping PH in check on indoor covered pool

[blentz]

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.

[PoolDoc]

We use uv for keeping water sanitary.

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.