A1624 14-Watt Power-Glo Fluorescent Bulb, 15-Inch T8 25 Mm diameter bulb fits standard and electric ballasts Simulates open water lighting conditions Close placement to water surface offers the potential to maximize light entry into the aquarium Generates very bright light; Adds a vibrant blue and white illumination Ideal for marine and African cichlid aquariums; 15-Inch length