How to Determine Reef Tank Lighting Requirements

The most important consideration in maintaining a healthy reef aquarium, with the exception of water quality, is lighting. Corals are demanding critters when it comes to light, and their requirements vary greatly by species. This article will show you what types of lighting and intensity you'll need to keep and grow a vibrant, living reef in your home.

Difficulty: Moderate

Instructions

Considerations for Reef Tank Lighting

1. Develop a budget. Lighting is the most expensive investment in your tank, so be realistic. Nothing good comes cheap or fast in a reef aquarium, but you can cut lighting costs by going with a smaller tank or choosing to keep corals that don't demand the most intense lighting.

2. 
    
   Stony corals like these demand more intense lighting than their softer cousins.

   Size matters. The bigger and deeper the reef aquarium, the more light it demands. As a general rule of thumb, figure 4 to 6 watts of light per gallon for low-light corals, and as much as 10 watts per gallon for light-loving corals. Remember, though, that a deeper or taller tank will require more light to reach its "cellar dwellers."

3. 
    
   This clam won't keep that lovely color without intense lighting.

   Decide what corals you want to keep. Corals are only one component of a reef tank, but they're the reason most people want to keep a reef in the first place. And corals are the critical factor in determining lighting requirements. Some of the "soft" corals, such as mushrooms, need very little light to thrive. Large-polyp stony (LPS) corals, such as brain and bubble corals, require moderate lighting, while small-polyp stony (SPS) corals are the most light-hungry of the bunch.

4. Consider your other reef inhabitants. Fish and invertebrates will be happy in a wide range of lighting intensity. There are some exceptions. That beautiful clam you're admiring in the show tank at your local aquarium shop, for example, won't stay so colorful without intense lighting. As with any live purchase for your tank, check with a trusted, knowledgeable source to make sure you have what's needed to keep the critter healthy.

5. Let there be light. Your basic options, listed in order of increasing intensity and cost, are basic fluorescent tubes, compact fluorescents (also called power compacts) and metal halide. If you're on a tight budget, consider compact fluorescents. They provide more wattage in a smaller space than regular fluorescents, produce much less heat than metal halides and will keep all but the most demanding corals happy. If money is not a concern and you're willing to put up with the heat, metal halides are considered the ultimate aquarium lighting system.

Tips & Warnings

• There's a price to pay for intense lighting. Many corals love to bask in bright light, but so do less desirable organisms, particularly the various pest algae that are the reef-keeper's arch enemy. If you increase the lighting, be prepared to step up your battle against algae. Light equals heat. Be prepared to install fans to dissipate the heat generated by intense lighting, especially from metal halides.