I have rune them on every tank I have had for year. The important thing to remeber is there main purpose is water clarity, whch if you have the correct wattage and flow rate, they do wonders. They do kill water bourne parasites but also kill everything that passes through them, HOWEVER, they do not kill any more beneficial bacteria than a skimmer does. I run mine only with the lighting since there are more beneficial bacteria and life forms that only come out in the dark, so I keep mine off then + it extends the bulb like. Like anything else, it pays to get quality, dont bother with a cheapy like Jebo, I run Aqua units and have good things about turbo twists.
