So are you saying that the pH is dropping and you are adding more pH Up to compensate? Or do I have that backwards and the pH is rising and you are adding more acid to compensate? Also, how are you chlorinating your pool and what is "Mr. Frog Chlorinator"?
Most pools that are chlorinated using a hypochlorite source of chlorine (e.g. bleach, chlorinating liquid, Cal-Hypo, lithium hypochlorite) will tend to rise in pH, depending on the TA level with higher TA having a greater tendency to rise in pH due to greater outgassing of carbon dioxide. If you keep the TA lower or use a pool cover, then the pH tends to be more stable.
Technically, as water temperature gets colder, the pH should rise somewhat, all else equal, and that's in addition to whatever pH rise occurs due to the TA. Standard pool water at a pH of 7.5 at 85F will rise to a pH of 7.7 at 55F and 7.8 at 40F even if the pool is covered so there is no outgassing of carbon dioxide to make the pH rise.
Richard
