After all the discussion about alkalinity in the pickling lime thread, I was playing around with some recipes in Bru'n Water today. I created a basic test recipe for a beer of about 50 SRM:
12 lbs 2-row
3 lb crystal 20
1.5 lb roasted barley
5 gallon mash (1.21 qt/lbs)
I added salts to get my water to approximate the "black malty" profile, and the mash pH estimate came out to be 5.5. Great! But then I scaled the grain and water 3x for a 15 gallon recipe, and the pH estimate changed to 5.3. Huh??
Am I doing something wrong? I can't think of any reason that the results aren't independent of batch size. The grain and water were both scaled proportionally, and salt additions scale automatically since they are written in g/gal.