WWC's 900g display has 12 radions. Yes that is a lot, however with a tank foot print of 12' x 4', that is one for every 4 sq/ft. Yes they also have T5 but only 6 - 4' bulbs for the entire tank. Considering that all of the lights are mounted 24" above the water's surface, it just goes to show how little light is required from these fixtures for amazing results.When you have the money or fame that those people have in order to get 1 radion per 1sq/ft then sure radions are amazing. Rather than spending more money on more radions I added t5 to my setup.