The Marine-GLO T8, 20 W linear fluorescent aquarium bulb delivers a powerful actinic blue light emission that is essential for all saltwater aquariums. The bulb emits an ideal blue light that highlights the fluorescent colours in corals and other photosynthetic invertebrates as well as provides the critical wavelengths they require for strong growth. The strong blue light is also effective at enhancing fish colours, accentuating blue and violet tones. This normal output bulb fits all suitable standard and electronic ballasts. It is recommended in combination with Life-GLO or Power-GLO, as well as for settings requiring added actinic blue spectrum. Size: 61 cm (24 in).