The long and short of the story is that the reef needs a specific type and quality of light. I could go on about color temperature, which is the whiteness of the bulb, or the CRI (“Color Rendering Index”), which is how natural objects appear while illuminated. The higher the CRI, the better the color rendering properties (see Glossary). Kelvin is a temperature scale, “lux” and “lumens” are for brightness. I have experimented with most commonly available lamps, trying to find the correct combination of lighting parameters recommended for a reef tank; I have always gotten poor results from these experiments.
To simplify the subject: buy the correct bulbs for your reef. There are many companies specifically dedicated to providing you with the correct bulbs. There really are no other common, inexpensive light bulbs that provide the proper lighting spectrum requirements for the reef.
The enclosed reef should have between 3 and 5 watts per gallon, and the lighting should stay on for no more than 9 hours a day. This means an absolute minimum of 3 watts per gallon, to an absolute maximum of 5 watts per gallon. For a 55-gallon tank, you will need between 165 and 275 watts. Remember the minimum is 3 watts per gallon, and the maximum is 5 watts per gallon. At 3 watts per gallon: 3 x 55 = 165. At 5 watts per gallon: 5 x 55 = 275.
Most experienced reef keepers change the bulbs for their tanks every 6 months, no matter what the factory rating. Any time over 6 months, and the light-loving creatures will suffer from not having the illumination they need in order to thrive. When you install new bulbs, you will see a noticeable difference in the photosynthetic livestock. Everything that is light-dependent will “come alive.” The benefits of proper lighting are amazing. We humans cannot tell the difference, but the reef livestock most definitely can!
