Quote Originally Posted by Rangeball
I'm confused. Which one is right?
From a technical point of view, more aeration means more outgassing of CO2 which means more of a rise in pH. However, there may be a point of diminishing returns and that may be what Jen saw -- that vigourous aeration caused more evaporation but not a noticeable increase in pH. She wasn't saying that aeration did not cause a rise in pH, but rather that extra vigorous aeration didn't seem to make the pH rise much faster but did increase the evaporation rate quite a bit. She found that a good tradeoff was made by doing some aeration that was less vigorous.

The processes that determine the rate of outgassing and evaporation are very complicated. Both depend on the surface area of the air-to-water boundary (including that boundary in droplets) but the specifics of the rates may be quite different. Nevertheless, if certain droplets were to completely evaporate, then you would lose both the water and the carbonate in that water into the air leaving only some salt (like sea spray) to eventually fall back to the ground or get whisked away by wind.

So I don't have an explanation for Jen's observation of an increase in evaporation without an increase in pH. I could imagine that there is a small increase in pH but that the rate of evaporation increases much more so that it appears that it dominates what's going on. The evaporation process may have a non-linear and more rapid runaway effect compared to the CO2 outgassing, but that's just a wild guess on my part.

Richard