Replying to my own question. After some experimentation it appears 7-8 oz of 31.45% 20 baume muriatic acid is required to completely offset the PH rise associated with adding 1 lb of 68% Cal Hypo to my 38000 gallon pool. So if i add 3 lbs of Cal Hypo need to add 21-24 oz of muriatic acid to stay PH neutral (at TA = 100). Can anyone else confirm these findings ? Thanks in advance.