Normal Florescent Bulbs
Normal Florescent or NO usually comes with a regular aquarium tank. This is enough for a fish-only setup. The NO bulbs tend to be cool and efficient; however, they are the least penetrating fluorescent bulbs. In aquariums with plants, they might be used as supplemental lighting.

High Output Bulbs
High output (HO) lights are available as T5 bulbs, which are smaller than the normal fluorescent. They emit more heat than the NO bulbs, but they usually come with a built in system to cut down on heat.

Very High Output Bulbs
Very High Output (VHO) comes in a variety of sizes; one of the most common is the T12. Although these bulbs emit heat, they don’t emit as much as a metal halide bulb. You get a more powerful light than the standard fluorescent. Unlike the metal halide, you get an even light source throughout your aquarium tank.

Power Compact Lights
These bulbs are designed slightly differently from the rest of the fluorescent bulbs. They have only one end cap attachment rather than the standard two, and the bulbs are available in different shapes from twin to square and triple. The bulbs are more efficient and powerful than other fluorescent bulbs. Power compact lights are smaller than normal fluorescent lights.

Metal Halide
This is a high intensity aquarium bulb that produces a focused light. The bulbs are used in freshwater and saltwater aquariums with plants and coral reefs. You will need to use a water chiller with these lights because they heat the water up and you might need a UV shield to cut down radiation. The bulbs are expensive and should be handled with care.

LED Lights

LED is not technically a light, but a light emitting diode. It is good for night time viewing of nocturnal fish.

LEDs are used increasingly commonly in aquarium lights. Particularly for reef aquariums, LED lights provide an efficient light source with less heat output to help maintain optimal aquarium temperatures. LED-based aquarium fixtures also have the advantage of being manually adjustable to emit a specific color-spectrum for ideal coloration of corals, fish, and invertebrates while optimizing photosynthetically active radiation (PAR) which raises growth and sustainability of photosynthetic life such as corals, anemones, clams, and macroalgae. These fixtures can be electronically programmed to simulate various lighting conditions throughout the day, reflecting phases of the sun and moon for a dynamic reef experience. LED fixtures typically cost up to five times as much as similarly rated fluorescent or high-intensity discharge lighting designed for reef aquariums and are not as high output to date.

LED aquarium lighting is most commonly used for nighttime lighting but has recently gained traction as being the main light source. Using an aquarium moon light has many benefits, especially for reef tanks. Moon lights complete the day/night cycle and can be synced with a timer to match the lunar cycle. Doing so can stimulate coral spawning and create great nighttime viewing. In addition to creating a cool shimmering moon light effect, LED lunar lights give you a window into what your nocturnal pets do at night. Using LED lighting as the main light source also has many benefits. LED bulbs are extremely energy efficient and last up to 5 years (50,000 hours). LED lights produce very little heat, are highly customizable and among the most handsome (and small) fixtures on the market today.