Mostly kills what's in the water that goes through the UV Sterilizer or comes in contact with the O3.
It's sometimes a good way to control the Ich parasite, but ever since the development of the Garlic Oil method, the only thing I've used either of those two gadgets for is to clear a phytoplankton outbreak(greenwater) with a UV Sterilizer.
Both methods make the water clearer but I like a natural reef aquarium. A greater variety of organisms grow better without UV, or O3, or a skimmer. Also, the power of Sunlight and Algae is still under-recognized in the hobby. But that's just me rambling.
Edited by Mark Peterson - February 09 2010 at 10:26am