Before You Buy Reef Tank Lighting

Most novice and many experienced saltwater aquarists are hesitant to start a reef tank or upgrade their Fish Only or Fish Only with Live Rock tank to a reef tank because they don't understand the lighting requirements of corals and they believe the high price of reef tank lighting is out of their reach. Here is a simple explanation of how much lighting you will need for your ​reef aquarium and light fixture pricing information.

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    Reef Tank Lighting "Rule of Thumb"

    A turtle in an aquarium
    ballyscanlon/The Image Bank/Getty Images

    The simple "rule of thumb" explanation of the lighting requirements for corals is three and a half (3 1/2) watts of over 6700K lighting for each gallon of tank water. For soft corals and four and a half (4 1/2) watts of over 6700K lighting for each gallon of tank water for hard corals. An example would be a 55-gallon tank would require 192.5 watts (55 X 3.5) of light for soft corals or 247.5 watts (55 X 4.5) for hard corals. There are exceptions to the rule of thumb (some coral species require more or less light than their hard or soft brethren), but for the most part, the "rule" is workable.

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    Lighting Types

    Fortunately (or unfortunately) there is a variety of lighting types available for today's aquarists to select from. Each type has its advantages (size, output, spectrum) and disadvantages (size, heat output, spectrum).

    Daylight or Actinic?
    Without going into a long-winded explanation, accept the fact that corals and other invertebrates (clams, anemones) need light in the 6700K (the light at the equator at noon) to a 10000K range. 20000K bulbs are also available and work well for reaching the bottom of deeper reef tanks. Corals will thrive without actinic light, but you may want to add an actinic light to bring out the blue and green colors in your tank.

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    Coralife Aqualight Double Strip
    © PriceGrabber

    Available in NO (Normal Output), HO (High Output), VHO (Very High Output), Actinic and 50/50 (half Daylight, half Actinic).

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    Compact Fluorescent Bulbs (CFL)

    Compact Fluorescent Light Bulb
    Photo by PriceGrabber

    Also known as Mini Twist Compact Fluorescent Bulbs, these bulbs are fairly new on the market. CFL's are power efficient, producing much more light in the right spectrum per watt than their incandescent cousins, using the same screw in fixtures. Cool running, efficient and inexpensive, these bulbs may be the reef light of choice for the future. These bulbs are not currently available in aquarium fixtures, but that hasn't been a problem for creative DIYers.

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    Power Compact (PC) or Compact Fluorescent

    Coralife Compact Fluorescent Bulbs

    These bulbs provide light in the daylight and actinic blue spectrum range. These bulbs produce twice the light as the same size fluorescent bulbs. Available in 6700K and 10000K.

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    Metal Halide

    Ocean Light Metal Halide

    A very efficient light for reef tanks, providing high-intensity light in the right spectrum range for reef tanks. Their downside is the amount of heat they produce and their higher cost for fixtures and replacement bulbs.

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    LED Aquarium Lighting

    PFO LED Light
    Photo by PriceGrabber

    While LED lunar lights have been around for a while, LED aquarium lights for reef tanks are just coming on the market. LED lights have several distinct advantages (low power consumption, low heat output, and long bulb life). While these lights are a bit more expensive, those who have used them are very pleased with their performance.

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    Light Fixture Size

    Determine the size of the area the light fixture will occupy. If you have a tank that is 48" wide by 16" deep, you won't be able to put a 72" light strip on it, but you can put 1 or 2 48" light strips on it. There are even some 36" fixtures which will work for a 48" tank.

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    Example 55g Reef Tank Light Fixture Choices

    Let's take a 55g tank as an example to see what will work for reef tank lighting:

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    Example 30g Reef Tank Light Fixture Choices

    Let's take a 30g tank as an example to see what will work for reef tank lighting:

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    Before You Buy

    Before you buy any reef tank lighting, take the time to compare prices and features. You will save yourself money and disappointments in the end.