SUNSUN Aquarium HBL-302 Hang on Back Power filter The flow can be adjust according to you need by the switch. Put the pump into the water than open the power just only, the pump can able to work. SUNSUN Aquarium HBL-302 Hang on Back Power filter includes 2 filter cartridges. Cartridges contain activated carbon which effectively removes pollutants and odors.� Suitable for Aquarium glasses up to 12mm.