The pump should be sized for the system to supply at least 1/2 gallon of water per minute per linear foot of pad system. Use a P-20 pump for systems 20 foot or less in length. Use a P-25 pump for systems 25 to 40 feet in length. Use a P-40S pump for systems 45 to 70 foot in length and a P50 pumps for systems 75 to 90' in length. Longer systems will require 2 or more pumps. To complete your installation purchase the optional plumbing kit. The sump should be sized for at least 3/4 gallon capacity per square foot of pad area. The sump is not a standard part of the Glacier-Cor System and must be purchased separately from International Greenhouse Company or obtained locally.