Oceanic's Low-Voltage 5 Watt UV Sterilizer will clarify your water and limit the spread of bacteria and parasites between tank inhabitants. This innovative design will fit neatly behind the Biocube filtration partition, in-between the Biocube return pump and return nozzle. You won't see the sterilizer, but you will certainly see the fantastic results! Designed for the 14 and 29 gallon biocube, although a clever hobbyist could surely use this sterilizer in a number of different applications. For best results, be sure to replace the U.V. bulb regulary. Every 8-12 months is recommended.