Adding Borates while lowering TA....

[Thinkly]

I have been embroiled in a week long battle to lower my TA. I am now down to 130 from 300+ following the acid+aeration+repeat procedure. I am shooting for a TA of around 100 for my fiberglass pool.

Now that I am approaching that mark, I am wondering when to start adding borax. I know borates are optional but I prefer them and already have a bunch on hand, so I would like to start adding. I can use the pool calc to estimate the effects on pH of adding borates but is this a good strategy?

It seems that I am going to need acid to offset the pH jumps and acid will also continue to decrease my TA, so I'm thinking that I start adding borates now while i am subsequently engaged in the TA lowering excursion. Good idea?

My current numbers:

FC 5
CC .5
TC 5.5
CYA 30
TA 130
pH 7.2 (currently aerating to increase following addition of acid)

 

[JasonLion]

It is simpler to finish the lowering TA process first, before starting in on adding borates. Lowering TA is more troublesome after you have added borates.

Assuming you hold PH constant, adding borates raises TA just a little. When adding borates you should aim to be PH neutral, i.e. end up with the same PH you started with. If using the borax and acid approach, there is a section in the Pool Calculator that tells you exactly how much of each to add to raise borates without changing the PH.

 

[257WbyMag]

As someone who has added borates in the past, I must advise you to make sure that you have your TA where you want before adding borates. It is markedly more difficult to lower your TA after adding the borates. This is by design though since borates are a supplemental buffer system. Don't be in a hurry. Just get your TA where you want it first.