Magic pH break point?

[steveinaz]

For the last 3 weeks my pH has held at 7.5. For the last 2 years I have had to use 3 cups of Muriatic every Saturday to keep it in check. This seems a little suspicious---I just got a new bottle of pH phenol red (Taylor kit) and my pH has been reading perfect ever since I got the new bottle.

Does pH finally correct itself? Should I be concerned about this?

[waterbear]

Where is your TA?

[steveinaz]

80ppm. It just seems strange that all of a sudden pH would stabilize.

[waterbear]

Has your TA always been at 80 ppm or has it been higher in the past?

[steveinaz]

It was around 120ppm last season.

[waterbear]

and there is your answer. High TA is one of the contributors to rising pH. When using stabilized chlorines like trichlor and dichlor a TA of aourn 120 will lead to pH stability because it ofsets the acidic nature of the chlorine source. With unstabilized chlorine sources which are more pH neutral, running a lower TA (90 ppm ot lower) leads to more pH stability since there is less outgassing of CO2.

[steveinaz]

...figures, I just bought 4 jugs of Muriatic a few a weeks ago....LOL

Thanks man for the explaination. I thought I would be adding acid for the rest of my life. :D

[waterbear]

You will still need the acid, just not as much. If you had gotten your TA down last season your pH would have been more stable then! If your pool has any substantial aeration such as waterfalls or jets then you might consider running your TA even a bit lower.