Originally Posted by ajf
If I treat my sparge water (using gypsum (I like hoppy pale ales)), I reduce the sparge water pH from 7.5 to 6.5, and if I stop the sparge at 2.5 brix, the pH of the final runnings is about 5.7
Something doesn't compute here. Adding gypsum to water doesn't change its pH (well it does but the shift is tiny). Also adding gypsum to mash doesn't change the pH unless there is unreacted phosphate i.e. you didn't provide enough calcium at dough-in.