I'm lookin about installing some light movers over my one frag tank instead of adding another halide. tank is 4'x2'x1' with a single 175 over it. Problem is that I've got bout 12-13" of clearance above the tank. I just looked up the dimensions on the light movers and it'll give me about 3-4" between the water surface and the mh bulb. Is that enough or too little?

