Luxeon Lime LEDs are new to the aquarium market and have a few significant advantages. The first advantage is the ability to adjust color temperature (CCT in °K) without sacrificing spectrum. To adjust color temperature for your lights, run all LED channels at full power and adjust the lime channel intensity to change color temperature. This allows for CCT adjustment without spectral degredation. You will get good, quality spectrum and CCT (K) by just adjusting the Lime. For example, in the past if you wanted more blue in your tank you always had to dim the whites. With Lime LEDs you can feel free to leave whites at the desired level, and simply adjust the lime channel instead. Second, the Lime LEDs provide broad spectrum around the ~560nm wavelength. Metal halide bulbs, a previous industry standard typically have a spectral output spike around 550nm. By using Luxeon lime LEDs you are able to better approximate an aquarium specific metal halide bulb with LEDs.