UV sterilizer

[clines4]

I've read alot of posts regarding uv sterilizers to help eliminate/reduce certain parasite and protozoan infections. I believe that there is some truth to this. The same function could also kill off beneficial organisms and bacteria that suspend in the water column. Is that not true also?

[HighlandReefer]

UV will kill or injure any organism that is small enough for the UV given the exposure time (water flow and bulb intensity). This will include most micro-organisms (bacteria included). When you consider the beneficial bacteria, there populations are quite numerous and IME are able to multiply fast enough to offset the UV kill rate. Hopefully this does not apply to the parasites that affect your fish. Their populations are not as numerous.

[bertoni]

Most or perhaps all of the filtration is done by microbes attached to a surface, not free-floating. A UV filter can help with some bacterial blooms, but not so much with diseases. Marine ich is far to large to be killed by a UV with the flow rates we use, for example. Protozoans likely are too large to be affected.