When my tank had ich a little while ago, I read in an old veterinarian fish book that UV light would kill it. Now, in a new veterinarian fish book, it says that a UV light can also kill off algae. According to it, if you filter under a UV light (not over the tank, of course), it will kill algae and parasites. Is there anything wrong that could happen here? Mutated algae/parasites? Killing something beneficial to the tank? Harming my fish somehow? This would be pretty temporary, as I'm probably going to get a lot of marimo balls when I go to my good NSLFS this weekend. I'll try to starve it a more natural way. If anyone is wondering, I have floating algae that makes the tank look like pea soup. Too much phosphates in the tap.