This article will discuss some of the more common aquarium lights (lamps) available as well as a few that are not as well known such as the SHO and T2 bulbs/fixtures.
Common aquarium bulbs include the:
*Metal Halide (MH); These are the reigning "Kings" of reef aquarium due to depth penetration, output, spectrum, and over all beauty and amount of coral life they help support. Even the newer T-5 lamps cannot achieve the depth penetration and overall output of these lights.
Metal Halide work via a gas mixture of halides and other elements. The actual light production comes from the small bubble of gas that is held in place by metal wires and/or supports. The electricity running between them and the small gas bubble, heats them, similar to an incandescent filament. This is one of the reasons that Metal Halide bulbs give off more heat than other bulbs.
The downside is the heat that MH lights produce, often resulting in the need for hood fans and even chillers. Two sizes I most often have used are the 10,000 K 175 watts and the 20,000 K 250 watts for really deep tanks (over 30")
*LED: The new reef compatible LED is likely to take over the market as they become more readily available, the price comes down and watts per lumen come up. These lights do not have the heat problems and are very compact. LED lights may prove to be more suitable for aquatic life tank-lighting and reef tanks because they offer superior flexibility when compared with traditional fluorescent lighting. When LED lights operate, the photometric radiation remains within a narrow band on the electromagnetic spectrum. Specific photometric wavelengths are often beneficial to some aquatic plant life and reef tanks. Controlling specific wavelengths becomes possible through a basic network of colored LED lights connected to a digital LED controller. Since LEDs emit light only in very specific direction, the installer has the option to illuminate a precise area by simply rotating the polycarbonate tube casing. The water resistant casing also provides the LED circuitry with adequate protection against moisture and chemicals found within the fish tank or reef tank.
So far the there are mixed reviews on the larger units such as the Solaris that replace the MH. The manufacturer of the Solaris claims "PAR light output levels equal to a 400W MH 20k. It uses 40% less energy than the 400W MH 20k fixtures it replaces. The life of the LEDs is approximately 50,000 hours, so it almost eliminates metal halide and fluorescent bulb replacements. All heat is radiated up and away from the tank; therefore, it does not heat the water like Metal Halides or Fluorescents. This eliminates the need for Chillers." However data shows 20 lumens per watt, MH bulbs provide around 50 lumens per watt as the output.
*T-12; a standard pin, 1-1/2" wide bulb. This bulb will generally use more watts per lumen output
*T-8; a standard pin, 1" wide bulb. As compared to the T-12, a 48" T-12 will use 32 watts, while a 48" T-8 will use 32 watts.
*T-5; Generally around 13 mm in diameter. This is a mini pin bulb which generally uses even less watts per lumen than many than T-8 bulbs.
*T-2; These bulbs are the latest technology yet. They measure only 7 mm and allow for several bulbs in a small space. A 13 watt 20 inch T-2 Bulb (6400 K) produces 950 lumens which is 73 lumens per watt in a very small space!
Quite bluntly, these T2 lamps and fixtures are about the best bulbs in a small space I have seen! These are very useful for small planted aquariums or Nano Reefs or even shelves for betta breeders. I expect these new T-2 lamps to sweep the smaller aquarium keeping hobby due to their extremely high efficiency and out put.
*VHO; this stands for "Very High Output". These come in T-5 thru T-12 standard fluorescent tubes and in the newer power compact (usually 4 pin) lamps such as the New generation Via Aqua Helios VHO. The new Helios come in a variety of sizes with outputs up to 180 watts out of lamps under 40 inches in length, which rival many Metal Halide (although not in depth penetration). These new higher output VHO fixtures/lamps have higher Kelvin and wattage output than previous generation VHO lamps/fixtures of similar size. These can be used for both marine reef applications as well as freshwater planted aquariums (these new VHOs are not scheduled for full release to the public until early 2008).
*PC; this stands for "Power Compact". These bulbs come in straight pin arrangements, square pin arrangements, and the ever more popular self ballasted standard incandescent fixture "screw in" type. These bulbs along with T-5s tend to be the most efficient.
A new Power Compact that in my opinion is awesome for planted aquariums and even for reef aquariums (as an addition to LED or Metal Halide) is the self ballasted SHO (Super high Output) PC bulbs. The 105 Watt SHO Daylight bulb puts out 6300 lumens and is comparable to a 525 watt Standard bulb (click on the picture for a link). This comes out to 60 lumens per watt, however this is a deceptive guide, as you can fit many more of these bulbs in a given space and also utilize more efficient reflectors.
The SHO can be mounted into your hood using a standard incandescent fixture or better, hung as a pendant light using reflector similar to how Metal Halides are commonly installed
For more information about aquarium lighting, please see this URL from which this article is snipped in the resource box:
