mittelhauser wrote:1) I've read in a couple of places not to worry about TA if the pH is o.k. At what point, do you really need to worry about the TA from a health and/or equipment standpoint?
Well, high alkalinity with a normal pH will drive the pH upwards naturally. And this will eventually cause scaling and might clog equipment. I've seen scaling at the waterline at pH 8.0 and 320 alkalinity. After a healthy dose of acid the pH was brought way down, 7.2, scaling disappeared, and water cleared right up. With a high alk keep your pH low to prevent such scaling, but you may have difficulty keeping it low because of its tendency to rise. There's no health issue with a higher alkalinity per se, other than the risk of cloudy water, and public pools may be closed due to turbidity.
mittelhauser wrote:2) I can't find *anything* online that draws a correlation between pool covers and TA. Is there any truth to his assertion? Is it the air or the sun which will affect the TA? If it is the sun, leaving the cover open over night isn't doing me any good...
-Jon
Well, a low pH with a high alkalinity causes the pool water to outgas carbon dioxide and this outgassing of CO2 is what causes the rise in pH. Do the experiment yourself by mixing vinegar (low pH) with baking soda (high pH) it'll fuzz CO2. This is exactly what's happening here, although on a smaller, less dramatic, fashion. The pool cover might slow down this outgassing and thus the pH would remain low. And the alkalinity would remain high.
To solve your high TA problem you want to do exactly the opposite, in other words *keep* the pH low, say 7.0 *and* get the CO2 out. Do this by installing a fountain on the return, or anything that can stir things up a bit, you want to get all the CO2 out. The alcalinity will naturally fall off.
