Ask Mr. Wizard

Brew-In-A-Bag Water Chemistry

TroubleShooting

Dave Allen, Indianapolis, Indiana asks,
Q

I recently switched to 10-gallon (38-l), electric brew-in-a-bag (BIAB) batches, from 10-gallon (38-l), three-vessel batches, and my beer quality has dropped to a depressing level. The first brew was a lightweight Hoppy beer that came out very flabby. No real personality, just sort of blah. The next was a darker beer with lots of flaked oats in the grist. It did not attenuate and is so worty as to be undrinkable. These batches have me questioning the mash chemistry as it relates to such a loose mix. I am using full PRE-boil volumes to mash, then draining the basket and putting the heat to it. With about 20 pounds (9.1 kg) of grain and 17 gallons (64 l) of water, am I diluting the mash so much as to make a water adjustment (or PH adjustment) necessary?

A
The first thing I do when discussing mash thickness is to calculate the liquor-to-grist ratio (water weight divided by grain weight) because this ratio is the basis for discussion related to thickness.
Response by Ashton Lewis.