Arcadia Marine Purple complements the white and blue lights in your marine aquarium. It is perfect for salt water habitats, showing off your fish, crabs and corals. The Marine Purple is a T5 lamp which gives it several advantages over the older T8 tubes. The T5 is 40% smaller in size, so can physically fit in more in the same space. The T5 has a better light spectrum The T5 has a higher luminance (Surface brightness of the lamp) The T5 has reduced power consumption due to the improved luminance rating, as it operates at a higher temperature. (This can provide typical energy savings of 30%) The T5 has a longer lifespan, up to 25% longer+ Reduced mercury levels used in the lamps Sizes Available: 24 Watt - 22\" / 55cm 34\" Watt - 34\" / 85cm 54 Watt - 46\" / 115cm