Test Mash Volumes

[dstar26t]

When doing a test mash, is it more important to get the water to grist ratio correct or the overall water amount correct including volume under the false bottom for the regular system which is a HERMS?
I'm doing a test mash with 3.5% of the grain, water and gypsum. The volume under the false bottom is 0.72 gal for my regular system, it will be zero for the test mash. When entering the full batch info into Bru'n water (Water Adjustment tab), if I leave out the volume under the false bottom, I get almost a 0.01 predicted pH valve difference. 9.50 vs. 8.78 gallons total.

Thanks,

Nate

 

[CadiBrewer]

Use the full volume because that's the volume of water you'll be treating. In my system,I usually use 1.33 quarts per pound when designing a brew. With the volume under my false bottom, that comes out to 1.4 quarts per pound. So for the test mash,I use one pound of grain in the proportions of the full mash, in 1.4 quarts of water.