TA question for vinyl pool


Well-known member
FC tonight was 3 (was 5 this am, been sunny ALLL DAY and was used a lot today, obvi adding bleach per calculator)
PH 7.4
CYA 45
But my TA was 170
My pool is CRYSTAL clear, but my husband insisted to check TA, as I don't really do it often. ( I mainly check FC and PH) But my sons eyes were red and he came in tested PH and was 7.3. I told him too hold out another hour or so, cuz I KNEW it would rise do to the activity of the pool. As for 4 days nobody used it. And of course the PH rose. But should I be worried of the TA?

Have had no other problems, and my still remains crystal clear. :whip:
My husband always wants to add Borax when PH is 7.3-7.2, and I think to hold off esp. when i know its going to be a long long weekend in the pool. So, advice?


TFP Expert
LifeTime Supporter
Jun 5, 2012
DFW, Texas
Hi maryj0w:

There are two reasons to lower your total alkalinity (TA)
  • 1. Because you want to slow down the rate that the PH rises
  • 2. If high TA is contributing to a high calcium saturation index (CSI) which puts you at risk of calcium scaling.
You shouldn't lower TA just to reach a target number.

Here is an article that explains more about TA: http://www.troublefreepool.com/pool-school/lowering total alkalinity

Do you happen to know what your Calcium Hardness (CH) is? With a vinyl liner it should be kept between 50-300 ppm. This will also impact your CSI (click the Pool Calculator link in my sig for more info)