Should I try to correct pH?

[jilted]

It's been raining here a lot lately and my pool has been going from a little low to high often. When it is high, it drains off automatically so I lose some water to that and also to evaporation and also I think I must have another leak that I have not discovered yet.

Also, when not raining, I'm also adding tap water maybe once a week.

Salt: 2800 ppm
CYA: 40 ppm
Alkalinity: 100 ppm
pH: 7.9
Free Chlorine: 2.0 ppm
Combined Chlorine: 0 ppm

I brought FC up to 10 ppm last Wednesday and already back down to 2 ppm FC. That prompted my CYA test I am going to bring it back up.

My actual question though is:
The pH has been borderline high for a few weeks now. It only takes 1 drop of reagent to bring it back down to 7.6 and I was wondering if I should adjust it or just see what happens.

Also, I use that "onBalance Simplified Formulas for Chemical Additions to Pools" but I don't see on that list how to figure out how much muriatic acid to use to lower pH for my pool size.

Thanks!
-stephen

Thanks

[waterbear]

Adjustments in pH are best done by adding a bit, waiting, and retesting or by using a demand test (if you have a K-2006 test kit). Treatment tables and online calculators cannot (I repeat, CANNOT) determine how much of a chemical you need to move the pH to a certain number since other factors also come into play.
As far as pH goes, many salt pools tend to fall into a range of 7.8 to 8.0 and stay there for an extended period (particularly if you have borate at 50 ppm in your pool too). Nothing wrong with that at all. Just be sure to lower the pH once it hits 8.0. If you don't lower it below 7.8 it probably won't rise as fast as lowering it to 7.6 or lower.

Having your CYA higher will not only keep the chlorine in the water, it will also indirectly slow the pH rise because there will be less aeration from hydrogen bubble genteration in the cell (because it will be on less to maintain the chlorine level) which means less outgassing of CO2. Keep the CYA at the manufacturers maximum recommened level (Compupool recommends 60 ppm but nothing wrong with 80 ppm as long as you keep the FC at 4% of the CYA level or higher). Also, dropping your TA to about 70 ppm will also slow the pH rise (once again because of slower outgassing of CO2).

[jilted]

Well that makes sense as to why it's not listed on the chart! :-)

There is a calculation on the chart for using muriatic acid to lower TA is that fairly accurate across pools not considering other factors? Can I do that while CYA is dissolving in the pool also or should I wait?

Thanks!

[waterbear]

the calculation for lowering TA is accurate in giving you an idea of the TOTAL amount of acid needed to lower the TA by a certain amount BUT you don't want to add more acid at one time than the amount needed to lower the pH to 7.0 and want to wait for the CO2 created to outgas (which causes the pH to rise again) and then repeat until the TA is where you want it. If you have added CYA and it is slowly dissolving in your filter then you can adjust pH and TA but remember that CYA is an acid and will also have a slight effect on pH.