You would think BIAB profile would be the one, but i've ran into a problem with it. I've been messing around with a sample recipe using the five gallon brew easy profile on beer smith. The recipe calls for 16 pounds of grain. The 5 gallon set up has a 7.5 gallon mash tun, using the BIAB mash profile, beer smith says i need a mash tun volume of 9.5 gallons.
The guys at Great Fermentations told me the 7.5 gallon mash tun will fit around 17 pounds of grain max.
Take it for what its worth. i'm by no means a seasoned brewer. But it's something i just noticed.
Well from my understanding is you put half the total water in the MT and the other half in the BK so you would never have the full volume in the MT at any given time so the MT would not need to be 9.5 gallons.