The top of the range in output and quietness , airstones are here and airline which needs to be 4mm is here are Aqua One SP360 Air Pump 2x180l/h Dual Outlet. Air pumps improve filtration system performance and overall water quality by increasing water flow which helps to eliminate localised build-up of toxic chemicals such as ammonia and nitrite 2 Year Warranty Dual Outlet 2 x 180l/h 4.5w No Variable Speed Control