Two brews one mash

Thinking about doing the following.

Brew 1: Imperial IPA

Mash 21lbs of grain for 90 minutes at 151 using 7 gallons
Sparge with whatever is needed to get me 7 gallon total into boil kettle. Assuming 50% Efficiency I get an S.G of 1.079.

(Using same grain bed)
Brew two: Baby IPA

Then Sparge 7 gallons at 170 for 15 minutes
Sparge again till 7 gallons in boil kettle
Assuming 75% Efficiency I get about half the first brew or 1.040

Does anyone have any thoughts on doing this? Also, I usually get between 75% and 80% Efficiency, but I have never calculated runnings. Does the 50% Efficiency make sense on the first brew?



Thanks all.

Doing it the old timey way, huh? The second "weaker" beer used to be called a "small" beer. Sounds like fun, although the second beer wouldn't make the cut as an IPA, might just call it a pale ale.

another thing you can do is to 'cap' the mash, and throw in a bit of something before your sparge to add a bit more body/fermentables to your smaller beer.

There are some good threads on this. Search for "Partygyle".

You can partygyle a IIPA and an IPA if you up the mash. Most partygyle brews are really more a 1/3 2/3 brew 1/3 big beer 2/3 little beer.