These new T5 lights provide more light output than T8s! Actinic 420 promotes the growth of zooxanthellae algae, essential for the growth and well-being of all live corals and invertebrates. Combine with Zoo Meds OceanSun for a more subdued deepwater tank effect. Combine with Zoo Meds UltraSun for optimum viewing pleasure of live fish and corals. Distributes the light evenly accross the water surface. Generates less heat as compared to metal halide lamps.