Aqua Medic T5 Reef Blue is intended for use in salt water aquariums with the lamp emitting almost exclusively blue light in the spectrum between 400nm and 500nm, peaking at 420 nm. These wavelengths enhance the growth of many coral species. In addition, when combined with T5 Reef White 10K they give the aquarium a most natural appearance. Aqua Medic T5 Reef Blue stimulates the natural effluorescence of corals especially if the aquarium is illuminated exclusively with Reef Blue during a simulated dusk or dawn.this T5 fluorescent lamp is available in the following sizes:-24 W - 55 cm-39 W - 85 cm-54 W - 115 cm-80 W - 145 cm