A crisp, ice-blue 10000K daylight spectrum. Replicates sunlight for deeper ocean environments with stronger emissions in the blue spectrum. The best lamp for the well-being of all photosynthetic corals and invertebrates. 55 Watt = 21" Long 65 Watt = 23" Long Compact fluorescent bulbs should be replaced every 14-16 months.Replacement is vital for the health of your livestock due to a 50% decline in spectrum and intensity.