Aquarium Lighting Levels

When you start keeping aquariums, you begin to realize that lighting is more complicated that you thought it was. Different types of aquariums need very different levels of aquarium lighting. These levels vary with the needs of the organisms that live in the aquariums.

  1. Fish-Only Tanks

    • In fish-only aquariums, you only need enough light to see the fish to your satisfaction. In fact, some species will actually get stressed if you add more than ambient light to their tank. For the vast majority of fish-only aquariums, you need less that 1.5 watts per gallon for adequate lighting. Normal output (NO) fluorescents can provide sufficient lighting for such a setup.

    Planted Tanks

    • If you want to keep live plants in your aquarium, you will have to up your lighting game a bit. Since plants depend on lighting to survive, you will generally need between 1.5 and 5.0 watts of lighting power per gallon of aquarium water. Low-light species will generally thrive near the 1.5-watt end of this range, while species requiring more intense lighting need light in the neighborhood of 5.0 watts per gallon. Powered compacts and other types of high output (HO) fluorescents can provide sufficient lighting for such an aquarium.

    Reef Tanks

    • Saltwater reef tanks require the most powerful lighting of all. Though coral are animals, photosynthetic algae live in their tissues and provide the coral with oxygen and nutrients. Reef tanks need intense lighting rated at a bare minimum of 5.0 watts per gallon. Advanced types of fluorescent lighting like T5 tubes can work for such a tank. For taller aquariums, metal halide bulbs work better, since these bulbs kick out light that can penetrate to the bottom of a deeper aquarium.

    LED Arrays

    • LEDs are the latest thing in aquarium lighting. LED arrays are more expensive, but their prices are dropping as more people adopt the technology. Also, they cost less to operate since their bulbs last at least 10 years -- compared to one year for fluorescents and metal halides -- and they require about a fifth of the electricity to get the same output as other types of lighting. The one catch with LEDs is that they do not follow the watt-per-gallon rule like other types of lighting. Instead, LED arrays come with PAR ratings. Most store-bought models have conversion charts on the box or the manufacturer's website to help you calculate the lighting needs of your tank in terms of LEDs.