For tanks up to 50 gallons. The 50 gallons rating assumes the unit is being used as a clarifier (algae) and sterilizer.8 watt T5 UV lampIn line or hang-onConnections: 1/2" or 3/4" ID Hose. You'll need at least four feet of clear hose.Requires powerhead--we recommend the Mini-Jet 404No tubing requiredDimensions: 20" X 4" X 2.75"For aquarium useBallast separate from unit