Flexzion Pond Pump Submersible Adjustable Frequency Inline Aquarium Fountain Waterfall Koi Fish Salt Fresh Water Filter with Set of Outlet Adapter This pump is good for aquariums, waterfalls, pond filtration systems or any other pond application Can be used submerged or inline (external) with both salt and fresh water, indoors or out Adjustable flow rate; Safe for fish, with no oil, copper or harmful chemicals Allow large size of dirt particle up to 1/4" with spiral propeller design; Energy saving up to 60% with electronic frequency conversion technology Well designed with variable frequency technology for a variety of settings: small power, large flow, high H-max, silence