ReefLux is the first true 10000K full spectrum metal halide bulb to be offered to the aquarium market. Other manufacturers claim to offer a 10000K lamp but that is just a marketing number of their best attempt to offer a full spectrum 10000K lamp. This is why they have a yellow or orange appearance and need to have some kind of fluorescent actinics to balance it out. Generally the more yellow or orange a bulb the more PAR the bulb will produce. ReefLux offers you the highest PAR rating without having to flood your aquarium with high powered fluorescent blue bulbs. The ReefLux 12000K has the performance of the 10000K but with a touch of blue added.