Low Mash Water in a Grandfather G30

[johndan]

I'm making a wheat in a Grandfather G30 and the recipe calls for a mash water volume of 2.6 gallons (with ~4 gallons of sparge water). I'm worried that that there won't be enough water to mash in the 11 pounds of fermentables—4 pounds of 2-row, 4 pounds of white wheat, and a pound each of flaked barley, oats and wheat.
Has anyone done a recipe with such a low mash water volume in a G30? Any suggestions? I could up the mash water to 4 gallons and reduce the sparge to 2.6 gallons, but that's going to reduce my efficiency, correct?

 

[johndan]

I asked the same question on the Grainfather subreddit, and someone suggested using Grainfather's formula for calculating mash water volume.

Grainfather's formula (grain weight in lb * 0.34) + 0.9 US gal) says to use 4.6 gallons of mash water. Odd that Brewfather's calculation is so different, given that I set my equipment profile to the G30 for a 60-minute boil.

Oddly, when I use Grainfather's sparge water calculation, the sparge water changes only slightly from Brewfather's volume (3.94 to 3.90 gallons). We'll see what happens…