Constant PH climb suddenly stopped

[geordie]

Thanks Richard, makes perfect sense. Yes, the fill water has high TA. Our "city" water is well water and has high TA and high ph. Since you explained the outgassing problem I completely understand it. (not really a problem... just a new twist).

I really gave up a long time ago on trying to lower the alkalinity in the pool. To lower the ph and keep it low enough long enough for aeration to work, is way too much trouble given that it all immediately begins to rise again from the fill water. Rain water doesn't appear to be much better as an additive.

Thanks for the help.

[duraleigh]

Richard,

That was a very insightful post.....I learned from it and I imagine others did as well....Thanks!

[tphaggerty]

Ha! That explains why my PH was low after leaving the solar cover on for 4 or 5 days last weekend when we were out of town. I have an SWG and my PH stays rock steady at 7.6, except this weekend, when it was somewhere between 7.2 and 7.4 (I have trouble seeing the colors that well).

[chem geek]

Ha! That explains why my PH was low after leaving the solar cover on for 4 or 5 days last weekend when we were out of town. I have an SWG and my PH stays rock steady at 7.6, except this weekend, when it was somewhere between 7.2 and 7.4 (I have trouble seeing the colors that well).

Well, now you've introduced another mystery. Something introduced into your pool is apparently acidic so that when you have the cover off with carbon dioxide outgassing this compensates so you have no net gain in pH. But that still leaves the question of what is driving your pH DOWN when the cover is on. I have no answer for that one! Anything unusual about your pool that could explain this?

Richard

[tphaggerty]

Well, here in NY the rain is pretty acidic. We had about 1" (or possibly more) of rain during that same period (which on a 20x40 pool is about 500gals). Does that work?

(Plus we had one small, very icky decomposing frog, but I think he was on the cover and didn't drop in until we took off the cover).

[chem geek]

Well, here in NY the rain is pretty acidic. We had about 1" (or possibly more) of rain during that same period (which on a 20x40 pool is about 500gals). Does that work?

Yup, that could do it if the rain were particularly acidic. You would have needed the rough equivalent of 4 cups of Muriatic Acid to go from 7.6 to 7.3 in a 24,000 gallon pool (my rough estimate from your 500 gallon, 1" number, assuming average depth of 4 feet and assuming a TA of 100). 4 cups of Muriatic Acid in 500 gallons of pure water would make the pH of about 4.

Richard