The SunSun HW-304B external 5-stage canister filter with built in UV sterilizer is ideal for tanks up to 150 gallon. It is capable of handling up to 525 gallons per hour with 4 flexible media trays that allow you to add your media such as SunSun's activated carbons, ceramic rings or bio-balls (each sold separately) to achieve excellent mechanical, chemical and biological filtration. The HW-304B has a built in 9 Watt UV sterilizer to help kill algae spores and bacteria, promoting clear crystal water. The HW-304B canister filter also has a convenient self-priming pump that eliminates the need for manual siphoning.