A UV sterilizer stops the spread of microorganisms from one fish/coral/invertebrate to another through the water.
The UV sterilizer utilizes a germicidal fluorescent lamp that produces light at a wavelength of approximately 254 nanometers (2537 Angstroms). The water with the bacteria/algae passes over the bulb (or around the bulb if a quartz sleeve is used) and is irradiated with this wavelength. As the light penetrates the bacteria/algae, it mutates the DNA (genetic material), preventing growth/multiplication of the organism.
Hate to bring this topic back alive but I am reconsidering purchasing one or asking for one for Xmas. Do I need a powerhead to use them or are they self powered as far as water movement goes. If not can they be hooked to a regular HOB (AC 50) filter inlet to move the water?