Surprisingly the actinic bulbs provide different coloration under the blue light than under the white light (Hayes 24), because the color you see of the fish is greatly impacted by the light used in the aquarium. “Warm” lights enhance the color of red and yellow fish, whereas the “cooler” lights give the fish a much more pale appearance (Hayes 22).
The choice between the two main types of lighting and the wattage of the bulb used should be dependent on the size of the tank, and the types of coral they include. For example, fluorescent is really only suitable for tanks up to eighteen inches deep, and metal-halide is essential for deeper reef aquariums. For general, soft coral reefs up to twenty-four inches deep you can achieve good results with 150-watt bulbs, although the result would be much better with a 250-watt bulb. But for more demanding species, start with 250-watt bulbs, especially if the depth of the tank is greater than twenty-four inches (Hayes 23). It is important to remember light reduces in proportion to the square distance from the source, Greater depth is the more light you will need (Hayes 8), therefore it is essential to use a minimum of four bulbs on tanks up to fifteen inches, and larger