Can't stabilize ph

[polyvue]

Hi cdingess,

How are you testing pH? With Taylor's phenol red drop test?

The CYA 80 ppm is a bit high, forcing you to maintain your pool with fairly high chlorine levels. Enough to produce a false high pH reading when using phenol tests.

It would seem like the pH is rising whenever you add bleach but it's probably just that the chlorine has affected the pH test. You could test this proposition by waiting to test pH when total chlorine falls below 5 or 6 ppm. Or borrow someone's pH meter to verify.

Or you could dilute your high-chlorine sample water sufficiently (with distilled water) to get a correct pH reading.

I think Taylor warns about interference with the pH test at chlorine levels above 10 ppm but my own testing leads me to believe the dark purplish color that affects the test starts at lower levels (maybe 8 ppm FC?)


"Do they make a ph stabilizer?"

Yep. Except you're already using it... Sodium Bicarbonate is a buffer, as is Sodium Tetraborate. I'm not sure TA 140 is high enough that I would want to lower it through the recommended 'Lower the pH and aerate' routine. It's a hassle and takes forever (a few days).

OTOH if your makeup water has much lower TA, it may be worth the time & effort to dump some pool water. This would lower your CYA, too.

Lastly, I assume when you say "bleach" that you mean sodium hypochlorite (liquid chlorine 5 to 12%) from the grocery or pool/hardware store. If you're adding other compounds, they could contribute to higher pH (not trichlor, which would just escalate your already high CYA).