I started doing partial boil/partial mash biab in my 5G SSBK. 1.5 gallons of water to 5 pounds of grains. I sparge with 165F water of the same amount. I drain the grain bag in a SS collander set on top of the BK & sparge their too. Allow to drain,maybe sqyeeze the bag a little. Then heat to a boil & right before it boils,deal with the hot break & start hop additions.