This water pump does not require a pre-filtration stage because it features a pre-filter system to prevent clogging and wear on the impeller. It is designed to be operated fully submerged and can be operated in line. Becuase it is made with environmentally friendly materials, they are fish safe and the motors are epoxy encapsulated, not oil filled. Features and Benefits: Pumps 1500 gallons per hour Can be used with or without a fountain head Flip up housing makes is easy to clean and maintain Ceramic shaft and bearings increase pump life