I use gallons, because its easier. So 9.25 lbs of grain is about 3 to 3.5 gallons of mash water. You figure you will lose 1 gallon per hour of boil, then for a 5.5 gal finish you need 3 to 3.5 gallons of water from sparging. Or if you screwed up the mash and your gravity, everything can change...