Does adding Boric acid raise TA

[Katodude]

So a few months ago I got my TA down to 60 and pulled the trigger and added Boric Acid granules. Got borates up to 50ppm. But a side effect (maybe just a coincidence ) is my TA went up 80. So after a weekend of torrential rain, and two months of adding a lot of acid. TA is back down to 70. Borates are now 30. Other stuff pretty much in line but some small adjustments needed.

So I have some left over boric acid and was wondering before I add it will it end up raising my TA which will decrease my ph stability (primary reason for adding borates)

Or did I just have some weird correlation that is not related.

 

[Saturn94]

(deleted)

 

[ajw22]

38 lbs of boric acid in 16,000 gallons will add 50 ppm of borates and lower pH by 0.29. PoolMath does not show any effect on your TA.

 

[JamesW]

Pure boric acid should not raise the TA.

What product did you use?

Are you saying that it went up to 80 or it went up by 80 ppm?

 

[Saturn94]

My bad. I have to raise pH each spring, as well as borate level, so I use borax to raise pH and boric acid to raise borates. It’s the borax that increases TA some.

That said, I don’t see any changes in pH stability (pH stays put all season; never have to add acid).

 

[Katodude]

I used the boric acid from Duda Diesel. It raised it to 80 (From 60).

 

[JamesW]

Assuming that it was pure boric acid, it should not have raised the TA.

Maybe it wasn't pure boric acid.

The difference is not that much. So, within the margin of error and precision.

Possibly something else is responsible.

 

[tillmac62]

What is the TA of your fill water?

 

[Katodude]

Fill water is high (120). But I did not add water before the jump. My TA has been stable at 70 for months. I worked hard to get it down to 60 before adding the boric acid. Then a day after I added it the TA jumped to 80. I went from having to add acid just once a week to twice a week after the borates add (which defeats the purpose of the borates add).

Just wanted to double check before I add again. Since I had a bunch of water dilution this weekend.

 

[JamesW]

B(OH)₃ + H₂O <> B(OH)₄^- + H⁺

Boric acid plus water <> borate plus Hydrogen ion (acid). The hydrogen ion will lower the pH.

Most of the boric acid remains as boric acid and does not become borate.

The borate contributes to the TA while the hydrogen ion subtracts from the TA for a net neutral effect on the TA.

If the boric acid really did increase the TA, then it likely had other boron compounds like tetraborate.

1÷(1+10^(9.2 – ph)) = percentage that becomes borate (molar basis).

pH..... % borate
7.2.......... 1
7.4.......... 1.6
7.6...........2.5
7.8...........3.8
7.9...........4.8
8.0...........5.9
8.2......... 9.1
8.4.........13.7
8.8.........28.5
9.2.........50
10.2...... 91
11.2.......99

At normal pool pH, less than 5% becomes borate.