Was putting together a recipe last night for the homebrew club and unfortunately in the presence of several potential users, ran into quite an interesting problem. As I was building the recipe, I saw I needed to reduce the mash pH from 5.61 to the target range of 5.4. So I added acidulated malt and the predicted pH went UP to 8.64. Hmmm.... Took the acidulated malt out, then added in lactic acid. The water calculator gave me what looked to be the correct amount but then again predicted the pH to be 8.64. Given the results I was getting for the amount of lactic acid, I'm assuming it gave me the correct amount of acid to add but it is displaying the wrong pH.