> Why do people use 32 watt bulbs? Aren't these 4 footers? Why not just get > four 40 watts and get more light, or use three 40 watters, and get the same T8-32w tubes put out the same amount of light as T-12 40w tubes, with the benefit of using less electricity. Also since the tube is smaller, more of the light reflected off the mirror/reflector will make it into the tank.