TA level before adding Boric acid

[pjoh2016]

Have a plaster saltwater pool. Current levels are ...
FC ~5
ph 7.8
TA 85
CH 420
CYA 70
Salt 3400

Want to add Boric acid to get Borates to ~ 40, but have read I should try to get the TA down to lower end of target range before doing so, as it might be difficult to lower TA after raising Borates to 40. Have tried multiple times to lower TA by adding Muratic Acid. The TA goes down, but then comes right back up when Ph rises. Have been able to get TA req Ph tends to settle out ~ 8.0 and TA back to ~90. This happens without adding any fill water to the pool. Can I go ahead an add the Boric Acid and just live with the higher TA level? FYI - my fill water does have a kind of high TA of ~120. So in summer, when have to add water due to evaporation, concerned about TA creeping up.

 

[JamesW]

I would add it now.

Watch the CSI and keep it between -0.3 and 0.0.

In my opinion, TA isn't any more difficult to lower with or without borates.

 

[pjoh2016]

I would add it now.

Watch the CSI and keep it between -0.3 and 0.0.

In my opinion, TA isn't any more difficult to lower with or without borates.

thanks

 

[JamesW]

Note that the TA will not rise when the pH rises.

TA can only rise by adding fill water with higher TA or adding something basic.

 

[JamesW]

Example 1:
pH 7.8
TA 85
Add 52 oz 31.45% muriatic acid to lower the pH from 7.8 to 7.2, which lowers the TA by 8.5.

Example 2:
pH 7.8
TA 85
Borate 50
Add 101 oz 31.45% muriatic acid to lower the pH from 7.8 to 7.2, which lowers the TA by 16.

So, with borates, you can add almost twice as much acid and lower the TA by almost twice as much.

In my opinion, the argument can be made that it's actually easier to lower TA with borates than without borates.

In any case, your CSI should be close to being good depending on the water temperature.

Just keep lowering the pH as needed to keep the CSI out of positive territory and don't worry too much about the TA unless the pH is rising too fast.

 

[Mdragger88]

I had good luck with my stubborn ta by lowering from 7.8 to 7.1 - the bigger drop moves my ta by about 5 each time i do this. You are aerating to bring ph back up not adding chemicals right?

 

[JamesW]

So, after a period of time, the pH will rise for both pools.

Example 1:
pH 7.8
TA 74
Add 46 oz acid to lower the pH to 7.2, and lower the TA to 67.

Example 2:
pH 7.5
TA 69
Borate 50
Add 46 oz acid to lower the pH to 7.2 and the TA to 61.

The borates buffer pH rise but the amount of acid that can be added is based on how much carbon dioxide has offgassed.

The amount of carbon dioxide is highest at lower pH.

The borate pool will rise from 7.2 to 7.5 in about the same amount of time as the non-borate pool will rise to a pH of 7.8.