What happens to pH over the winter?

[UnderWaterVanya]

What does the pH tend to do when the pool is closed? Does it go up or down in a reliable trend?

 

[Christian]

It should stay mostly the same though may raise a little bit. It won't drop unless there is a source of something acidic to drop it.

 

[UnderWaterVanya]

It should stay mostly the same though may raise a little bit. It won't drop unless there is a source of something acidic to drop it.

Thanks - I asked because I was looking at CSI numbers and trying to determine what mine would look like over the winter as temps drop etc.

My current numbers:
FC 12
pH 7.8 (measured even though above 10 - I've had pretty good luck with a quickly read test - but I will not take action until I'm below FC 10 just to be sure)
TA 70
CH 260
CYA 50-55
Salt Unknown but > 0 (none added except via Chlorine)
Borates unknown (none added by me ever)
water at 70 degrees
Vinyl In ground pool

Assuming Salt is 500ppm for the heck of it:

CSI: negative 0.05
(so far so good... even with Salt at 0ppm this is a -0.02)

With water temp down around say 50 degrees and chlorine down to 3 this drops to -0.24, and if I drop the pH to 7.2 the CSI index is now an aggressive -0.8! With Vinyl this may not matter, but I'd like to know before dropping pH that far.

 

[UnderWaterVanya]

This post may answer my question indirectly...