I've got 4 gallons of holiday ale I'm going to bottle/mini-keg today but I need some clarification. I want to put 1.3 gal. of it in a mini-keg and bottle the remaining ~2.7 gal. How can I calculate the amount of priming sugar to use? I know i'm supposed to use less for the keg but I am unclear on the amount. Any help is greatly appreciated!