Malt for an ale should start out at about 4 pounds per gallon of water. This will give you the taste profile desired for an ale (a little sweeter than a porter). The amount of malt needed can vary depending on how much sugar was present in the original barley and how dark you want your final product to be. If you are making a porter, then you will want to use about 8-10 pounds per gallon of water because porters are typically darker and less sweet than ales.