Evan,

Whoops! I missed that part about dumping the whole box. If he dumped an entire box in, then the combination of 4 cups of acid and a box of Borax in a 2800 gallon pool (with 100 TA, 30 CYA) would have a net rise in pH from 7.5 to about 7.9 (close to his measured 8.0) and adding about 6 ounces of acid would bring this back down to 7.5 and 6 ounces is in the 3/4 to 1 cup range you suggested.

So I'm sorry I didn't read his post thoroughly and thank you for correcting me!

Richard