Perhaps Martin Brungard and/or Kai are able to weigh in on this....
I've been using Kai's water sheet for my last couple beers (German Pils, Helles, a Maibock coming up next week) and with all the recent chatter on this board about Bru'n Water, thought I'd check it out as well. And I'm having trouble getting the predicted pH to match up. As a test, I used Kai's "Pilsner Water" recipe which calls for 100ppm Gypsum, 85ppm Epsom, and 130ppm CaCl2 added into distilled water, and a grist of 98% Pils and 2% Acidulated. Both worksheets match up at this point, telling me to add the same amounts of the right salts, giving RA of -47, etc etc.
But it is in the next step that things go south. I loaded my basic pils parameters into both sheets: 17.64lbs pils malt, 0.36lbs acidulated, mash at 2qts/lbs (9 gallons strike water) and collect a total of 16 gals pre-boil, which is boiled to 11 gallons. And somehow Kai's sheet is giving me predicted pH of 5.36 (which would be nice), and Martin's is saying 4.9, which is too low.
Can anyone confirm something similar? Or are these sheets always going to differ in how they calculate pH from the SRM? Or am I doing something wrong? I believe I have zeroed out all things like lactic acid additions in Martin's sheet but maybe I missed something. Kai or Martin, I can email my working copies of your sheets to you if you want to check them out.