Originally Posted by photogscott
One option is to just stuff more grain in the MLT to counteract the inefficiency(how much I wouldn't have a clue)
Here's how I do it: At 1.25 qt/lb in the mash, 0.1 gal/lb absorbed by grain, and a target of 7 gal in the brewpot, 10# is where my system is "balanced" (meaning the 0.5 gal/lb sparge water gives me the brewpot vol I'm looking for).
My efficiency on a 10# mash is typically 75%
For every pound I add over 10 and up to 15, I figure I'm going to lose 1% efficiency.
For every pound I add over 15, I figure I'll lose 2% efficiency.
I've only had one big beer to test this on so far; on a 20# mash I got ~62%. So my estimate seems to be pretty close. I'll just keep tweaking it as I do more bigger beers. (Or until I get a bigger brewpot and can always use 0.5 gal/lb to sparge)