T-Style Fluorescent Tube Lamps

are the most popular style of aquarium lighting. There are a wide range of lengths, colors and brands available and fluorescent tube lights are very cost efficient due to the large market for them. The only disadvantage is these bulbs do not have a very high wattage output compared to other lighting options. These lights are ideal for freshwater and fish only aquariums and may need to be doubled up or more to support high light requirement corals.

Normal Output fluorescent lights have wattages of 14 to 40 and are lower light output compared to HO and VHO fluorescent bulbs.

High Output fluorescent lamps have wattages ranging from 24 to 54 watts.

Very High Output fluorescent lamps range from 75 to 165 watts in output.

T style bulbs are also assigned a number after the T, such as T-5 or T-8 or even T-12. The most common type of T lamp in aquariums are T-5 and T-12 bulbs. The numbers stand for the diameter. The t number divided by 8 will give you the diameter in inches of that bulb. Example: a T-8 style bulb has a diameter of 8/8 inches, or 1 inch. A t-12 bulb has a diameter of 12/8 inches. To find out what T number your bulb is, measure the distance from one edge to the other across the lamp, not end-to-end. It will be between .25 and 2 inches. Once you have your measurement convert that number to an improper fraction over 8. The numerator will be your lamps t number.

End of Life: Tube fluorescents should be replaced anywhere from 4-18 months for NO and VHO styles, HO bulbs can be replaced every 16 to 24 months. Replacement is needed when the lamp loses intensity or color rendition. End of life varies between brands and types but can usually be known when you see dark rings moving inside the tube or the light flickering on and off.