Jennie,
I guess I wasn't clear. Total Alkalinity is linked to pH and generally moves with it. If your pH goes down, T/A goes down. If your pH goes up, T/A goes up no matter HOW you raise it.

Except: Aerating when pH is 7.2 or lower is the only way we can "break" that link and get pH to up without T/A going up as well.

We can also raise T/A without raising pH (much)--by adding baking soda.

So using Borax to raise pH causes the normal linked rise in T/A.

But if you use Soda Ash it's like adding BOTH Borax AND Baking Soda and it causes T/A to rise a lot more than Borax.

Still, as WaterMom says, you can usually use Borax without worry. However, if you are still in the process of lowering T/A, and pH is 7.2 or lower, you can use aerating to raise pH as our normal procedure.

CAVEAT: If your pH is below 6.9 you'll want to raise ASAP with Borax, especially in a vinyl pool.