Actually since my pool is AG I learned not to worry about alkalinity. Testing showed that as alkalinity increases the greater my pH would fluxuate. With alkalinity low, pH is stable as a rock. See this string of posts - http://www.poolforum.com/pf2/showthread.php?t=7870. I have not checked it in years but am confident my alkalinity is very low.

I added 2 boxes of Borax and pH has come up to normal.

This has me perplexed as well.

Jim