Originally Posted by trreherd
dill i dont belive black lights are relly ultra-vilet i think they are close though
If they were reel ultra-vilet than i dont think people would be selling them.
Actually, they really are ultraviolet. You can hurt your eyes loking at them too long. My grandad had a black light he used to use to test mineral samples for fluorescence (rock hound - could have been worse - could have kept a ton of fish tanks :) ). Their fine so long as you dont stare at them or keep them on all the time.
I'd hesitate to use one in a fish tank, though. Maybe the UV cold cathodes are less energetic... Essentially, if it's powerful enough to sterilize the bacteria, then prolonged exposure will hurt the fish. That's just my opinion, but I think my reasoning is pretty sound.