I was planning to do a Pliny The Younger clone as a BIAB and figured I'd do a gallon first since this will be my first batch using grain. I plan to use scottland's recipe:
http://www.bertusbrewery.com/2013/03/pliny-younger-clone-20.html
For a gallon batch, the grain bill is about 3 pounds, but I need to hit 70% efficiency to get the proper OG. I'm assuming I'll need to use 1.2 gallons to have 1 gallon make it to primary. Here are my questions:
Is a 9 quart cooler is big enough to handle 1.2 gallons of water with 3 pounds of grain in a 29" x 29" mesh bag?
If I plan to do a 90 minute rest at 145, what temperature should I heat the water up to (I'll put a towel around the cooler)?
If after my 90 minutes of mashing, I do a dunk sparge at 170 and let the bag continue to drain during the 90 minute boil, will I hit 70% efficiency?
Obviously no one can perfectly answer my questions, but for those of you who have used a particular amount of grain in a particular sized cooler for a 1 gallon batch, you can make a good guess based on how much your temperature held/dropped and what kind of efficiency you achieved.
I might also just do a PM with 1.5 or 2 pounds total grain because I'm sure a 9 quart cooler can handle that, and then I can measure the OG after the dunk sparge and know how much extract I need to add to get the proper OG regardless of what my efficiency is.