I've been shopping for a UV and see the Jabao 36 watt on Amazon for basically free. The reviews are all great too. I'm hesitant because my priority is to kill the bad guys that could be introduced into my setup. Clarifying is important but not my priority. I'd plan on running it with an empty FX 5 on my 640 gallon setup. Does anyone have any experience with these? Do they sterilize not just clarify?