TA and Borax

[MoebiusStreet]

I'd like to add Borax to my pool. The instructions here say to first get the TA into position. My pool seems not to want to budge from the range of 90-100, and I'm wondering if that slightly higher value means I should wait.

A little background. The reason I want to add the Borax is probably interrelated with the higher TA in the first place. This is a new pool, it's only been running a couple months. I'm finding that the behavior of the pH is that I'll add acid to adjust to around 7.5, but it jumps very quickly back to 7.8, and then drifts up to 8.0 over the next day or two. And despite all the cycles I've gone through of this pattern, the TA doesn't really change much. I wonder if the newness of the plaster is the cause of both the higher TA and of the pool's insistence that it wants its pH to be at least 7.8.

So maybe the Borax will address both sides of this - holding the pH lower, while making my TA lower simply by the 3-4 gallons of acid I'll need to dump in.

Anybody see problems with this?

 

[jblizzle]

How old is the plaster?
What is the TA of your top-off water?

 

[JasonLion]

Adding borates will slightly raise TA, despite the added acid.

The process you describe of adding acid regularly and waiting for PH to go up, will lower TA, but only very very slowly. It often takes quite a while for TA changes to become apparent.

 

[chem geek]

I wonder if the newness of the plaster is the cause of both the higher TA and of the pool's insistence that it wants its pH to be at least 7.8.

Yes, the newness of the plaster is probably adding calcium hydroxide to the water which increases CH, pH and even TA. So adding acid just brings the pH and TA back to where they were. Are you noticing any increase in CH? If so, then the new plaster explains this.

If you were to add Borates to the pool, the additional pH buffering would slow down the rate of pH rise, but it would not change the amount of acid you have to add. So you would add more quantity less often, but the total amount per time would be roughly the same. If that's what you want, then you could add the borates. Just don't think it will reduce your acid consumption since it probably won't.

 

[UN1017]

A couple more things to think about:

1. What is your fill water TA?
2. Is there a reason you have only been knocking the pH down to 7.5 and not to the 7.0-7.2 as recommended in how to lower your TA?