It is designed to empty marine and RV holding tanks of normal waste. It is also an excellent choice for emptying fish boxes of scales and residual waste. A flow rate or up to 12 gallons per minute conveniently empties any tank in minutes. The unique four- blade design ensures waste is ground up throughly. The pump is self-priming to a five foot lift when impeller is wet, four foot loft when impeller is dry, but for optimum performance an life, it should be mounted as close to the tank as possible. Marine pump out must be in proper discharge zones only. The macerator will not handle hard objects,rags, or feminine napkins.