So my dad has a 75 gal that is about 12 yo and the quad t5 unit just broke an he is wondering if a single Tao would get the job done cuz he doesn't have the money for 2 right now. He only has green hairy mushrooms in it which just about cover all the rock from end to end and he doesnt want any other coral. Would a single unit with no optics sustain them? Or would he need to have a second?