BLUE DEPTH is our 20,000 Kelvin lamp series and it has been designed to bring out your corals' bold and vibrant colors. Keepers of larger polyped stony corals, such as Acanthastrea, brain, and hammer corals, are especially pleased with the intensity of color achieved in specimens under this lighting scheme. Very commonly, aquarists like to add 20,000 K lamps to a mix of warmer colored lamps for better balanced results in both color and growth of aquarium specimens