Quote Originally Posted by jenmenke
Why should I expect PH to go up? I think I'm confusing myself. Let me ask this:

If I wasn't aerating and added muriatic acid to address my high alkalinity, should I expect my PH to go down THEN? Because, like Carl says, alk and ph sort of tag along together?

... but by aerating I will combat the tendency for the ph to drop because of the added acid?

sorry. just trying to get my arms around this so it makes sense and I can remember it.
Normally, pH and alkalinity move together, so when you add acid, they both go down. (You'll have to look at Ben's stuff to get the exact details, but here's my recollection of how it works) At lower pH, aeration causes carbon dioxide gas to be given off by the water. This removal of carbon is what actually helps. The aeration process raises the pH, but since the carbon has been gassed off, your TA stays down.