What is my ideal TA?

Mangoman1 · Postby **Mangoman1** » Mon 13 Aug, 2012 20:56

My new house has a 38,000 gallon salt water pool. This is my first pool and I can't quite lower my Ph from 8.6 no matter how much acid I use. My alkalinity was at 80ppm so I figured I needed to bump that up to 90ppm, but I still can't get my Ph to come down. What I my ideal TA, and/or is there anything else I could do?

Postby **chem geek** » Tue 14 Aug, 2012 00:54

See Water Balance for SWGs. Your TA should be lower, not more than 70 ppm. Your CYA should be up at 80 ppm if your pool is in full sun and your FC target at 4 ppm. You might also consider using 50 ppm Borates.

To lower your pH from 8.6 (how did you measure that?) down to 7.7 with your TA of 80 ppm would take 77 fluid ounces (9 cups, 5 ounces) of full-strength Muriatic Acid (31.45% Hydrochloric Acid). Your TA will get lowered by about 8 ppm as a result and that's fine.

Mangoman1 · Postby **Mangoman1** » Mon 20 Aug, 2012 22:14

Thanks for the reply and the link...

I measured my pH using a Pentair Pool & Spa test kit...the pool guy who the previous owner used said this kit was recommended.

A TA of 70ppm? I was at 80 and thought that was too high...guess this kit of mine isn't as great as I thought.

Should I make these adjustments now even though I will be closing in about four weeks?

Postby **chem geek** » Tue 21 Aug, 2012 00:56

That's up to you. You should get yourself a better test kit, at least for the start of next season. Get either the Taylor K-2006 or the TFTestkits TF-100, with the latter having more of the reagents you use the most so is more economical.

Hellen · Postby **Hellen** » Mon 01 Oct, 2012 04:22

Optimum TA is from 80 to 120 mg/l.
Good luck,
Regards, Hellen

Postby **chem geek** » Tue 02 Oct, 2012 00:48

The optimum TA depends on the amount of aeration in the pool as well as if a saltwater chlorine generator is used. With an SWG or when using a hypochlorite source of chlorine, a lower TA is better since it reduces the amount of carbon dioxide outgassing that causes the pH to rise. TA is a measure of the over-carbonation of the water and is a SOURCE of rising pH in its own right.

If one wants more pH buffering without causing the pH to rise from carbon dioxide outgassing, then after lowering the TA one can use 50 ppm Borates. To keep the saturation index near zero for plaster surfaces, one can target a somewhat higher pH (say, 7.7) and a higher Calcium Hardness (CH).