Extremely quiet and powerful air pumps for increasing oxygen levels, running air-driven ornaments, and operating undergravel filters. CE certified, TUV/GS tested - safety and reliability assured Designed in conjunction with leading sound engineers for maximum noise reduction High flow rates of air, even in deeper aquariums Modern design and state-of-the-art technology Adjustable airflow 3 year guarantee Application 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 a TetraTec AS air stone, or to an air-powered ornament. It is important to install a TetraTec CV4 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.