Lighting Systems

Fluorescent Lighting

Fluorescent lamps come in many types that vary in terms of their intensity, color, and the amount of electricity they consume. The most important of these factors from a purely aesthetic point of view is the color. Ever notice how people appear unhealthy under industrial fluorescent lighting? This is because the lamps typically used in such applications are the "cool white" type. This lamp imparts a yellowish green cast to everything, although it is supposedly the best for illuminating a work area. If you have ever taken a color snapshot (using film, not a digital camera) with only this type of lighting and no flash, you can see the green coloration.

Each type of fluorescent lamp has its own color rendition. Various lighting manufacturers produce 5000-5500°K fluorescent lamps under different brand names. If your aquarium shop does not stock them, check with a lighting company in your area. You can also check out the following Web site to find out the lumen output of typical 40-watt fluorescent lamps: http://palimpsest.stanford.edu/byorg/abbey/an/an16/an16-4/an16-406.html.

Getting the Right Amount of Light

The best aquarium lamp type, in terms of color rendering, is rated by the manufacturer in the range of 5000-5500 Kelvin degrees (°K) or higher. The Kelvin scale is a method of comparing the overall spectral quality of various light sources; the math used to derive this number is of no interest to us. Suffice it to say that the range I suggest is comparable to the color of sunlight near midday under an overcast sky. Such lighting makes the fish and invertebrates natural hues sparkle. It is worth noting that a common commercial use of such lamps is to illuminate produce in the grocery store. Since grocers know we buy produce mostly by its appearance, using special lighting has obvious advantages. \_/

Fluorescent lamps come in stock sizes. The longer the lamp, the greater the light output and the amount of electricity consumed. Thus, 40-watt lamps are four feet long, 20-watt lamps are two feet, and so forth. If you are going to use a fixture that sets on top of the tank, and this is the most common design, you will be limited to the lumen output of a certain lamp size, for example, two feet for a twenty-gallon tank. You can always purchase an additional fixture, or one that accommodates two lamps. Once the tank reaches four feet in length, the lighting options are greater. For example, you can purchase an inexpensive fluorescent fixture, or "shop light," at a DIY store and hang it above the tank. Two of them will fit nicely side by side, giving you a total of 160 watts of lighting, enough for many photosynthetic species. You will need to allow for some headroom when working on the aquarium, as well as protect the units from water damage. Hanging them with a pulley system that allows the height to be adjusted works well.

Hanging lights over the tank may not appeal to you, and the finished look is certainly industrial. If the tank is built-in, of course, you can hide the lighting on the other side of the wall. For most of us, none of these will be an option, and we will use an enclosed "hood" or "canopy" that provides both a top for the tank and a housing for lighting equipment. Wood or laminate canopies that match the aquarium cabinet create a finished look to free-standing tanks that is hard to beat. You can purchase a canopy with up to four fluorescent lamps or with metal halide lamps.

The heat-producing transformer, or ballast, needed for fluorescent lighting may be dealt with in one of two ways. In the most common design, the ballast is located in the power cord and sits underneath the aquarium or on the floor, out of the way. Protect the floor finish with a cork pad if you place it there, as the ballast may get too hot to touch. For multiple fluorescent lamps, the ballast is often located within the lighting hood itself. This is because the needed wiring gets complicated, and you would have a fat bundle of cable running from the ballast up to the lamps. To prevent overheating, the manufacturer may install a small fan, such as the one in your computer, to ventilate the hood. A multilamp fluorescent hood may offer you the best balance between cost and lighting efficiency for tanks up to four feet long.

56 Saltwater Aquarium Models

56 Saltwater Aquarium Models

Metal Halide Lighting

My personal preference for aquarium lighting is metal halide. It provides the very bright light needed for a larger aquarium installation and is hard to beat for light output, color rendering, and durability. The lamps usually last about three times as long as comparable fluorescent lamps, which lose intensity with age. On the downside, metal halide costs considerably more, both for the initial installation and for replacement lamps. Further, the lamps get hot in operation and can be extremely dangerous if broken. Proper design, though, deals with these issues adequately. There are two options: hang the fixtures at intervals above the aquarium (sort of like the lighting above the bar in many restaurants), or use an enclosed hood similar to that described for fluorescent lighting. Hoods containing metal halide lamps absolutely require ventilation via one or multiple fans, and the lamps must be shielded from any contact with water by a clear, heat-resistant plastic panel or tempered glass. All these features contribute to the greater cost. If you are planning a tank much larger than fifty-five gallons, however, metal halide will give the most satisfactory results. A four-foot tank needs two lamps (about 150 watts each) and a six-footer requires three.

Manufacturers of metal halide equipment for aquarium use generally supply them with 5000-5500°K or higher lamps. Besides providing appealing natural coloration, metal halide lighting produces "glitter lines" as it passes through the constantly moving water surface, a decidedly realistic touch. Fluorescent lighting, being diffuse rather than a point-source of light, does not produce glitter lines.

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