Just a quick question hopefully. I'm using Bru'n Water and love it.
My water is high in bicarbonates and low in sulfates. For hoppy pale beers, I usually treat my tap water by diluting it 50% with distilled and then adding back gypsum. I usually treat the brewing water all at once except for sparge acidification. For this particular beer, I'm adding 1.3g of gypsum per gallon.
Using the sparge acidification tab of Bru'n water, I've also been using 10% phosphoric acid to lower the sparge water PH. The sparge acidification tab lists the starting water PH...per my water report, it's 6.9. However, didn't I already lower the water PH with the gypsum additions? If so, how do I calculate the the new liquor PH so I can recalculate the sparge acid addition?