Don, first you figure the gallons of water that the pool holds. (Don't ask ME how....). Then since each gallon has 16 cups, you add 2 packs of Jell-O for every gallon.....I think you may need your credit card (Or Bert's) to buy the Jell-O.

Lime is generally the Preferred Flavour, but any will do. I'm partial to Strawberry Banana myself.