Bill,
Right in this section are several stickied threads on alkalinity and aeration.
The short answer is you are right--you aerate to re-raise pH without increase T/A.
You can aerate by pointing the returns right along the surface.
You can buy a cheap fountain sprayer that screws into the return outlet (they were a sale for $6 or $7 just last Sunday.) This does a FANTASTIC job of aeration.
A gang of 12 year olds works too.
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