I think LED light is really a feasible and suitable light source for frag tanks. Not like most main display tanks, frags tanks are often shallow and the water volume is not so big. For a independent frag tank system, MH or other light source which generate considerable heat may cause temperature problem to the corals inside the tank. Using a low-radiation LED light source certainly solve the problem. I do not mean that with a LED light, there is no need to lower down the temperature. But a hang-on type cooling fan instead of a energy-wasting chillier a enough to maintain the water temperature. So, if anyone of you are interested in setting up a frag tank, take LED light into your consideration! You will be happy with the result! LOL~