So I’ve got a 7 gallon kettle and am considering my first MIAB, the question is: can/should I mash with 5 gallons and then top off for a full volume? Im sure it will change efficiency and pre-boil gravity, but how significantly? Or am I best off just boiling with 6 gallons? My concern is that with 6 gallons of water, and the 12 lbs. of grain in the bag, I’ll run out of room in the kettle?