Tetra Air pumps are uniquely designed very powerful and extremely quiet. Available in a range of sizes they are suitable for increasing oxygen levels, running air-driven ornaments, and operating undergravel filters. Tetra Application Guidance: Place the air pump outside the aquarium, away from areas where it may get splashed. Attach a length of standard airline to the outlet, and run this into the aquarium. Attach the airline to an air stone, or to an air-powered ornament. It is important to install a check-valve in the airline to prevent water being drawn into the pump. Use the flow-control valve that comes with each APS pump to control the amount of air produced. Always read the instructions carefully before use.