Does Borax Really Raise Ta That Much?!

[Parrick]

For a long time I have been reading about the benefits of borates so I decided to try it out. I had a 3LB can of Leisure Time pH Balance Plus on hand (97.98% boric acid, 2.02% sodium carbonate anhydrous) so I added that to my 1525 gal swim spa for 41ppm borates (per Pool Calculator). My intention was to use 16oz of 20 mule borax to bring the borate level to 50ppm. Out of curiosity I punched in 16oz of borax into the Pool Calculator to see what effects it would have & it said that that small amount would raise my TA by 20ppm!!! Is that correct? I run my TA at around 40-50ppm & have had good results with very slow upward pH drift in the past. Hopefully boric acid does not have the same dramatic effect on TA (Pool calculator does not have boric acid in the list for "Efects Of Adding Chemicals") Most of what I have read indicates that adding borates has a minimal effect on TA so now I am confused. Thank God I didn't use borax for the whole thing! That would have been 90oz of borax which the Calculator says would have raised my TA by 115! AM I MISSING SOMETHING? It would take a lot of work to counteract that much rise in TA!

[Parrick]

Well the good news is that the boric acid did not affect my TA...I'm still dead on 50ppm. It did lower the pH by about 0.15

[chem geek]

Borax raises both pH and TA, but for increasing borates you would add acid as well and that lowers pH and TA so the net result is only a very small increase in TA. Basically, adding Borax and acid is equivalent to adding boric acid except that doing the former results in additional sodium chloride salt.

50 ppm borates at pH 7.5 will contribute 5 ppm to TA.

[Parrick]

Interesting. I always appreciate your expert insight, Chem Geek. You are THE MAN around here! I have never had to lower my TA, just bump it up a bit on rare occasion, but as I recall the process is basically aerate, test, add acid, test, repeat. I also notice per the Pool Calculator that borates increase the amount of acid required to achieve the same pH drop. Seems like it would take a lot of time, testing & acid to counteract even a 20ppm TA increase. I think I will stick with the boric acid option. Is the "additional sodium chloride salt" significant? Is there a downside to the boric acid method?

[chem geek]

Boric acid is somewhat more expensive than the equivalent combination of 20 Mule Team Borax and Muriatic Acid. When using dry acid, I suspect boric acid is about the same price.

50 ppm borates (ppm Boron) increases salt by 129 ppm so not that much.

You generally lower the TA before you add the borates since it's easier to move the pH up or down before the borates are added.

[AquaParadise]

"I'd been trying to get an initial TA of around 80+ before making any other adjustments (per your sticky post)"

This is confusing me also.

[chem geek]

What is confusing you? It's easier to lower the TA level prior to adding the borates. The reason is that the pH swings more easily without the borates so adding acid to keep the pH lower (around 7.0) while doing aeration has the pH rise faster without borates so it's easier to tell when you need to add more acid. Also, when you want to raise the pH at the end of the procedure by aeration alone without acid addition, it's easier to rise when there are no borates. Once you add the borates, the pH will be more difficult to move, be it via chemicals or via aeration.