Does air temperature affect pH? How about water temperature?

[rvlittle]

During the spring and summer months, our pool (an outdoor pool) WAS maintaining pH readings ranging from 7.4 to 7.
As the weather has cooled (sometimes REALLY cool) pH readings have consistently bee at 8 or more and we've been going through tons of muriatic acid.

Summer water temperature is 78 to 80 degrees, and in the winter it's kept at 68 to 70 degrees
To paraphrase Slim Pickens, what in the wide world of sports is a'goin' on here?

[aylad]

I don't think that air temps directly affect pH, but they do affect how fast chlorine is used up--and high chlorine levels will give falsely high pH readings. Have you shocked the pool lately, and maybe the chlorine levels haven't come down yet?

[chem geek]

As water temperature drops, the pH rises if all else were equal. This due to the temperature dependence of the various pH equilibrium reactions. This natural effect tends to keep the saturation index from changing as much when the temperature changes.

However, at cooler water temps, the rate of carbon dioxide outgassing should be slowing down so I would have expected the pH to become more stable. So I don't understand why you are using so much more acid; the pH tending to rise more is a mystery.

[rvlittle]

" . . . the pH tending to rise more is a mystery. "
As of 12/14 - it's still whacked (sigh).