For tanks up to 125 gallons. The 125 gallons rating assumes the unit is being used as a clarifier (algae) and sterilizer.25 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 606 No tubing requiredDimensions: 26" X 4" X 2.75"For aquarium useBallast separate from unit