UV Sterilizers are both incredibly simple and astoundingly effective. Water from the aquarium flows into a cylindrical shell wrapped around a water-tight light chamber. Within the chamber is a powerful ultra violet light source which basks the water in high frequency electromagnetic energy.

Ultra Violet light actually alters the molecular makeup of living cells, killing free floating bacteria and parasitic organisms (like Ich). The sterilized water then flows back into your aquarium, clean and clear.

The effectiveness of a UV sterilizer depends on two things: One, the speed of the water flowing about the light source. Slower pump flows yield more effective filtering, increasing 'light time.' Two, the length of the light bulb. Larger lights sterilize more water by virtue of their size.