I just got a bottle of 85% food grade phosphoric acid and I used a spreadsheet to dilute some of it down to a 10% concentration. When I plugged all of my numbers into Bru'n Water, it says that I need 46ml of 10% acid to bring my mash down to 5.2. I'm brewing a Blonde Ale, BIAB 4 gallon batch. 5# 2 row, 8 oz carapils, and 5 oz aromatic malt. yellow balanced profile, with 5.6 gallons of RO water. I'm also adding 1.5 grams of gypsum and 1.5 grams CaCl. When using 88% lactic acid, I only have to add 5ml.
46ml of 10% phosphoric acid seems high to me. Does it take that much more to move the pH? Or did I do something wrong in the spreadsheet?