The type of lighting that we will select for use in our saltwater aquarium is largely dependant upon the grouping of livestock that we will select to inhabit the tank. Regular cycles of light are commonly used to simulate day and night for fish and invertebrates. This encourages a feel of a natural environment among our livestock, cultivating the proper periods of rest and similar such circumstances that are most conducive to their successful and healthy adaptations to our aquariums.
Tanks containing only fish and live rock do not commonly require overly specific lighting techniques. However, invertebrates and the required propagation of various forms of algae that are commonly needed indeed calls for more specific and customized lighting. Choices for lighting our tanks include natural sunlight, Light Emitting Diode (LED), various forms of fluorescent bulbs, and metal halide lights.
Natural sunlight is only effective as a light source for a saltwater aquarium in geographic areas located in the vicinity of the equator. This is due to the levels of intensity of sunlight found in such areas. Such aquarist techniques involving the use of sunlight and in the vicinity of the equator are only implemented among large reef tanks. In tanks that are much more commonly found among hobbyists throughout the world, natural sunlight is avoided as a light source as it is potentially detrimental to many forms of livestock for a variety of reasons.
LED sources have a great deal of potential. The jury is somewhat still out on the extent of their practicality and effectiveness, however, so it can depend on which expert we ask as to how they will evaluate LED. One way or the other, the aquarist community would be well served to keep a watchful eye on evolving technological developments among LED light sources, as implications currently include advances in lighting schedules, simulations of lunar lighting, and even the effective simulation of cloud coverage.
Different types of fluorescent bulbs all have about the same intensity, but it is their various shapes and reflectors that result in their unique specifications. The newer fluorescents have improved reflectors, allowing more amounts of light into the aquarium than in years past. The more recently designed bulbs are a bit more costly to maintain than their predecessors, so some aquarists continue to use traditional fluorescent lighting sources.
Metal halide lights are comparable in practicality to fluorescent lighting. Many aquarists consider the primary difference to be that metal halide may be concentrated into specific areas of the tank while fluorescent light is distributed evenly. Metal halide lighting systems are usually more of a financial investment than fluorescent lights, but are required for certain reef tanks.
Overall, it will depend on the specific types of livestock that we desire to maintain as to the importance of our choice for lighting. This is of course directly related to the amount that we should be willing to invest in our lighting and the extents that we will go to achieve and maintain our optimal light conditions.
