I know several local reefers who use UV. There's a lot of debate as to if it does more harm or good, but honestly, their tanks look pretty good. It's not all that different than running ozone.
I heard it filters, or starilizes to much even the good stuff. Just trying to prevent parisites and diseases in the future. I just got my first ich out break.
__________________ Tony K.
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75 Gallon Reef Tank
Livestock: 6 Chromis, Atlantic Blue Tang, Yellow Tang, Flame Angel, Pair Maroon Clowns, Bristal Star
Corals: Bubble Coral, Toadstool Leather, Star Polyp, Zoo's, Mushrooms, Clam
It can filter out some beneficial bacteria, but the vast majority of it lives in your rock and sand, not in the water column. That being said, it's not goint to prevent or cure ich either. It just doesn't have the capacity to "sterilize" a tank, for better or worse.
Mostly in our hobby it's used as one method to remove the "yellowing" from water - some use UV, some use GAC, either can work. . IMHO never use a UV steriliser without a controller. People typically use an ORP monitor hooked up to their UV unit to control dosing. Can be easy to overdose if you just leave it on 24x7 which potentially could have dire consequences. If you do go the UV route make sure you size your unit correctly. UV can be dangerous to people. You would need a sizable UV unit to actually sterilise harmful bacteria from the water and a decent contact time, something that your typical home reef unit is just not going to be able to do. Not sure what else to add. I know many people that use them with great success. I believe there is a Podcast here which talks about UV, well worth the listen!
I sell these UV units at my shop. 90% or so are sold for the sole purpose of pond water clarification. Some of the newer models have elaborately designed helix's within the unit in order to increase the exposure time. UV can be dangerous to people, but you have to be very careless to get a dose that would do more then give you a very bad sun burn. The UV lights can damage the retina of the eye. UV light damages the DNA of cells, this is how UV unites clarify or sterilize water. High doses of UVA radiation can destroy some of the function of algae and therefor is used in clarifier's. UVA,B,and C radiation can and does change the structure of DNA with in cells and is used in "sterilizers" the cost of the glass that allows B and C radiation through accounts for the higher cost of the bulbs.
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