Recommended Lighting for Reef Tanks

Lighting for reef tanks depends on several factors. The type of bulb and the corals you keep will determine the type of fixture you need. Reefkeeping requires a bulb with a spectrum of 10,000 to 20,000K. The intensity of the bulb is also a factor. Certain corals prefer certain spectrum and light intensity. Consider which corals you will be planning on keeping before you decide on the type of lighting.

  1. Metal Halide

    • Metal halide fixtures use either single-ended screw-in bulbs or double-ended HQI bulbs that plug into place. Metal halide bulbs are the highest power form of aquarium lighting, and the bulbs can range up to 1,000 watts. Some fixtures have multiple bulbs. They put out a lot of light, but the downside to metal halide bulbs is that they put out a lot of heat and use a lot of electricity. Because they produce so much heat, the housing should be equipped with fans to keep the bulbs and sockets from overheating. HQI bulbs also need a fixture with a glass shield that blocks the ultraviolet rays they emit.

    Compact Fluorescent

    • Compact fluorescent bulbs are not as bright as metal halides, but they have the advantages of running cooler and not requiring as much power. The bulbs are also significantly cheaper than metal halides. Compact fluorescent bulbs resemble standard fluorescent bulbs bent in a "U" shape. They have either two or four pins. The four-pin configuration consists of either four pins in a line or in a square. Compact fluorescent bulbs 13 watts and under use two pins, and higher wattage bulbs use four.

    Light Emitting Diodes

    • Light-emitting diodes, or LEDs, are a relatively new form of aquarium lighting. They come in a wide variety of color temperatures, and are mainly used for supplemental lighting. A fixture that uses metal halides or compact fluorescent bulbs for daytime lighting might use LEDs for lighting at night to simulate moonlight. LEDs use much less power and run significantly cooler than either metal halides or compact fluorescent bulbs, but they do not emit as much light. You will need many LEDs to equal the output of a single metal halide.

    Fluorescents

    • Standard fluorescent bulbs are classified by the diameter of the tubes. T5s are 5/8 inch, while T12s are 1 1/2 inch. T8s are in the middle at 1 inch even. Fluorescent bulbs are also classified according to their light output. Reefkeeping requires high output or very high output bulbs. Fluorescent bulbs have a lifespan of approximately 6 to 12 months. They should be replaced on schedule, whether or not the light is still working, since the quality of the light can degrade with age. Fluorescent bulbs are cheaper than compact fluorescents, but they do require an external ballast.