PH has risen significantly

[joemkraus]

I follow all of the guidelines here and have had no issues in 1.5 years. My PH rose (which of course it does via adding liquid chlorine), but after adding significant amounts Muriatic acid (couple of pints) it is staying high via the drop test. Very odd as adding a small amount of muriatic acid usually makes a significant difference. Maybe my red drop solution is getting old, ordered some more. any ideas?

 

[YippeeSkippy]

Liquid chlorine has zero effect on pH. Within minutes of adding liquid chlorine it is pH neutral.

I hope your new reagent for the pH test solves this dilemma.

Maddie

 

[mknauss]

The use of liquid chlorine does not raise the pH throughout its use cycle in the pool water.

Your pH will drop when you add acid. You do need a TA test value to determine how much acid to use for the drop you are targeting.

The reagent may be bad. Or, what is your FC?

 

[joemkraus]

My free chlorine is about 6.0. That’s funny that you say that liquid chlorine does not affect pH I have always found that liquid chlorine slowly lowers the pH and tablets slowly raise the pH. Since I generally only use liquid chlorine I have to add acid every other week or so a small amount but consistently to bring it back down

 

[mknauss]

Trichlor tablets are very acidic. They lower the pH of the pool water.

Liquid chlorine is pH neutral. Water pH will naturally rise due to aeration and alkalinity.

 

[joemkraus]

Maybe it’s not The liquid chlorine that is raising my PH maybe it’s just the water in our area not sure but in any case usually a small amount of muratic acid lower back right away

 

[asusundevil]

I've owned pools in AZ for the past 23 years and never once been able to stabilize my PH level. It's aggravating but not atypical.

 

[mknauss]

maybe it’s just the water in our area

Test your fill water for TA and CH.

 

[HermanTX]

Maybe it’s not The liquid chlorine that is raising my PH maybe it’s just the water in our area not sure but in any case usually a small amount of muratic acid lower back right away

Each 8 ounce trichlor tab will add 5.5 FC, add 3.3 CYA and drop PH by 0.29 in a 10,000 gal pool. So since you have 22k gals it would be about half of those values.
As indicated by others LC should not have any influence to your rising pH.

 

[mgtfp]

I wouldn't say that liquid chlorine has zero effect on pH, but it has zero net effect - over the whole chlorination cycle. Adding bleach will raise pH, the following use of chlorine (disinfection, oxidation, UV-decay) is an acidic process which will bring the pH back to where it started once FC is back where it started (ignoring other effects on pH).

Within normal maintenance bleach additions, you hardly notice a thing. For example, if you bring your FC from 6ppm to 8ppm (i.e. lower target FC range to higher target FC range for CYA 50, covering a typical daily FC-loss of 2ppm), then (assuming TA 80ppm) pH will rise from 7.6 to 7.7 - hardly noticeable in a drop test. Once FC is back to 6ppm, pH will be back to 7.6. Often, the bleach effects are hidden behind the pH-drift by aeration.

But when doing a SLAM, the pH-rise by adding larger bleach quantities is very noticeable (at least with a pH-meter, drops tests won't work anymore at SLAM-FC). That's why it is important to lower pH before starting a SLAM. And again, once the SLAM is over, pH will get back down to where it started (plus pH-drift by aeration that occurred in the meantime). In above example, adding enough bleach to get FC from 6ppm to SLAM-FC of 20ppm, would raise pH to nearly 8.6.

Here are a few references to chem geek posts about the effect of bleach on pH, and the whole cycle being pH-neutral:
Will a digital pH meter read accurately at high chlorine
Worry about PH after adding liquid chorine
Equations for Chlorine Chemistry