Size: 18"Wattage: 15W Our Reef Sun bulb has a 50/50 combination of 6500K trichromatic daylight phosphor and actinic 420 phosphor in the same lamp. It provides high intensity full spectrum illumination, strong in the short wavelength blue region essential for photosynthetic corals and invertebrates. Zoo Med's Reef Sun bulb is balanced with 6500K daylight for natural color enhancement and viewing pleasure. Ideal for all marine aquariums, reef aquariums, African cichlids, and discus fish. Zoo Med's line of fluorescent aquarium lamps are made in Europe for ultra high quality, color, and longer burn life. Our energy saving T-8 sizes can save you up to $30.00 per year in electricity over the thicker T-12 size lamps!