I guess I should probably say this a little better since I have a moment. Uv is usefull for simple algaes and bacterium depending on size of the unit. Talking to a friend that is in water sterilization field has given me quiet a bit of info in the past. As a good rule the uv unit should be about 1/2 your gallons in watts. Flow rates vary based on what you are trying to accomplish but 2-3 turns per hour will cover you pretty well. If you are trying to cure ich or some larger parasite/ viral infection you can pretty much forget it. But as a back up to help with secondary infections its a good help unless the medication says differently. But for startup id not use it.