A.Y. McDonald 23150L Stainless Steel Pump End Only 15 GPM 1.5 HPA. Y. McDonald offers a full line of four inch submersibles ranging from 1 3 through 5 horsepower, with flow rates ranging from 5 through 25 GPM. The 23000 Series stainless steel submersibles offer peak capacity performance in 5, 7, 10, 15, 20, and 25 GPM models. All L Series Stainless Steel Pumps come with a 1 1 4 " discharge and sizes range from 1 3 to 5 horsepower (HP). Two wire models up to 1 1 2 and three wire models up to 5 horsepower (HP). A.