I've searched the forum and found at least one post where someone says that TA can't increase on its own.
My pool is 14 months old and after about 11 months of adding about a gallon of MA (in 30-36 oz. portions) every week my pH finally stabilized somewhat. I now go through a gallon of MA in about 3 weeks or so. My TA ranges from 70 to 90 between MA additions, but it always creeps up before I add MA and it goes back down to around 70 (sometimes I get 60) after I bring the pH down to 7.5. Here are my most recent numbers:
pH 7.5 (after adding 20 oz. of MA yesterday)
Borates 50 (maybe slightly less with recent rains)
My question is why does TA continually rise? The only thing that's been added to my pool (other than MA) is rainwater which I thought would lower the TA, not raise it.