Lighting your Saltwater Aquarium

Proper lighting conditions in saltwater aquariums are important for two reasons: they enable photosynthesis to occur, and they replicate the lighting conditions of whatever water depth to which your aquatic creatures are accustomed.

Minimum Requirements The minimum lighting requirements for your saltwater aquarium will depend on what the fish tank contains. If it's a fish-only environment, a standard fluorescent bulb should be sufficient. Provide about three to five watts per gallon of water for 10 to 12 hours a day. With reef tanks or saltwater aquariums, more intense light will be necessary. Dark blue lights best mimic the natural environment of deep sea dwelling creatures. For reef tanks, provide two to five watts per gallon by using metal halides or a combination of full spectrum lights and actinic bulbs. Corals need 12 to 14 hours of daily light.

Reef and Corals
Corals and anemones need light for photosynthesis. Blue light best imitates how sunlight changes as it reaches the sea depths. However, don't rely too heavily on one type of lighting source. Coral species prefer different spectrums. Hard corals need brighter light, while soft corals can get by with less intensity.

Metal Halides
Metal halides are very intense and definitely the best lighting source for saltwater and reef tanks. They can be found in any spectrum. Metal halides are expensive and very hot. Bulbs will need to be replaced every six months. Keep metal halides positioned about 12 inches above your tank, and provide a fan or chiller to negate their heating effect.

Dos and Don'ts
Don't leave aquarium lights on all day. Do buy a timer to provide necessary rest periods. With complex ecosystems, don't rely on a single lighting source. Do as much research about coral's lighting needs as you can before introducing it to your tank.

Actinics
Actinic lights promote the growth of algae beneficial to corals and invertebrates. Because actinics are dark blue they should be balanced with full spectrum bulbs. We recommend using one actinic bulb and one daylight bulb per 30 gallons of water. /p>

Daylight Bulbs
A combination of an actinic bulb and daylight bulb is a cost-efficient alternative to using metal halides. Daylight bulbs are full spectrum lights that imitate the appearance and visible spectrum of sunlight. Daylight bulbs are given a CRI rating, which stands for color rendering index. Daylight bulbs with CRIs near 100 come closest to imitating the sun.