Does adding Boric acid raise TA

Katodude

Silver Supporter
Aug 22, 2017
1,206
West Palm Beach/Florida
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.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
21,141
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
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

TFP Expert
Mar 2, 2011
21,509
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

Well-known member
Mar 11, 2015
1,028
SE Virginia
Pool Size
20000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
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).
 

JamesW

TFP Expert
Mar 2, 2011
21,509
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.
 

Katodude

Silver Supporter
Aug 22, 2017
1,206
West Palm Beach/Florida
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

TFP Expert
Mar 2, 2011
21,509
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.
 
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