Biab

I'm new to brewing and have done a few extract batches and would like to try all grain. Anyways, ive been looking at doing a biab recipe, but need some answers. If the recipe has a boil size of 7.5 gallons, does that include the grain or is that just the water? If its just the water, how much more do i have to account for per pound of grain? I'm trying to figure out what size of pot to buy. Ive got a 36 quarts pot now and hoping it is big enough for the average brew.

36 quarts will work for small grain bills (maybe 8.5lbs of grain with a boil size of 7.5 gallons if lucky). If you have a boil size of 7.5 gallons then you need to add .125 gallons per pound of grain for grain absorption. So a 10lb grain bill would be .125 X 10 = 1.25 gal (grain absorption) + 7.5 (boil volume) = 8.75 (total water volume).

Thanks. Yep, looks like im off to buy a bigger pot lol

With a pre-boil volume of 7.5 gallons I would assume your recipe is a 6-6.5 gallon recipe. If you scale down to 5 gallon recipes you would only need a pre-boil volume of 6-6.5 gallons which would make your 36 qt pot more effective, since you could fit more grain in the pot...

Yeah I did BIAB with 30qt. Pot for a while doing 5g batches. You might not be able to do full volume no sparge but you can mash in that easy then lift and pour sparge water over it.

My standard protocol for beers up to 1.060 is to mash in 7 gallons of water. I do squeeze out some after I pull the bag but not excessively. I usually get about 6.25 gallons preboil volume and a bit over 5 gallons when I'm done. I use a 40qt pot with steamer insert. I don't really brew high gravity beers so that setup works for me. If you want to go substantially higher than 1.060 I would go with a 60 or 80 qt pot.

Getting ready for this as well. There is a cool calculator on the forum called BIABinfo. Its called "The calculator" and its a sticky I think. It will use your grain bill and your desired OG to tell you the amount of water to use for the mash. Great for scaling recipies that may have been designed for standard AG.

Yep, establish the typical sized beer you will brew (considering that you can always add dme for high gravity beers) and use this calculator to see where you fall.

Under can you mash it.
http://rackers.org/calcs.shtml/

You want about an inch and a half of space from the top for stirring.

If you are torn between two sized pots, I'd recommend getting the larger one, you won't regret it!