Natural pH levels? Influence of TA?

[linust]

Greetings! Found TFP before we bought our house last year...first experience with a pool. I've been follow TFP/BBB with (I believe) good results...water has always been clear & sparkly, and fairly easy to maintain (apart from trying to figure out the booster pump plumbing and valves and now needing to figure out some main pump air leaks).

All last year, pH would constantly rise from 7.5 to 7.8 (one or two days later) and then on up to 8.2 if I let it go to a week. I know that our water features aren't helping, but is this normal? At the height of last summer, I found myself adding about 1 pt of Muriatic Acid each week. During the summer, TA stayed around 70. Sometime last summer/early fall, a couple major squalls hit, seriously overfilling/diluting our pool...TA fell to about 50. I lowered pH to about 7.6 then raised TA targeting 100 thinking higher TA should help stabilize pH. I think I overshot a bit...at 10 drops, TA test goes from green to dark grey then pink with the 11th drop.

At any rate, I don't seem to have changed much, apart from now using a bit more MA to lower pH the same amount.
So the question is...how much do I need to chase pH?

Here are this afternoon's test results:
FC - 3.5
CC - 0.5
pH - 8.2
TA - 110
On the FC/CC, I'm chasing some small pockets of algae in some cracked mortar but this isn't new

From a week ago:
CH - 210
CYA - 40

Thanks!

 

[Patrick_B]

Welcome to TFP!

You should chase pH and not TA. It is vastly more important. Right now you have 8.2 or higher...and that should be your concern. At your TA and CH levels I wouldn't worry much, IF your pH is right. I would get that 8.2 down immediately. pH is what creates problems, high and low. TA is tied to it and can't be separated, but you need to chase that pH until it is right and make sure it stays right.

Also, I would make sure that FC doesn't drop any. If it were mine, I would bump it a little and keep a very close check on it.

 

[JasonLion]

High TA both helps stabilize PH and puts upward pressure on PH. When there is aeration the PH will always be going up at least a little, more slowly when TA is lower. Likewise the lower you try to maintain PH, the faster it will go up.

Depending on how much aeration you have, you may be able to get PH to settle down by keeping TA around 60 and seeing if PH will stabilize below 8.0. If that doesn't work, you can add borates and let TA go down to 50, which will slow the PH increase some more. Most pools will stabilize at one of those points, though in rare cases PH still increases, though not nearly as quickly as what you are seeing now.