When it comes to aquarium lights, LED (Light Emitting Diode) is the new kid on the block. Although the reef world dove into LEDs in a big way, the freshwater world has been a bit slower to embrace the use of LED lighting. That's not to say it has no value or is not suited to freshwater aquariums; in fact, there are some excellent applications for LED lights in freshwater aquariums.
The benefits of using LED lights are many.
They take less energy to run, in fact quite a bit less. LED aquarium lighting uses up to 80% less electricity than other aquarium lights. They also do not generate the heat that fluorescent light bulbs do. Another very popular plus is the fact that they last far longer than standard fluorescent bulbs.
LED lights can be dimmed and programmed, allowing for a natural dimming at sunset and the reverse at sunrise. This is particularly good for nocturnal fish, as a dim blue light can be left on the tank to simulate moonlight and allow for feeding and viewing purposes. Last, but not least, they come in a variety of colors, which can be used to accent the tank in interesting ways.
Low Energy consumption.
Low heat output.
Adjustable light intensity.
At the onset of LED lights, there were a number of negatives, but over time the technology has improved to the point that there are very few cons for this type of light.
Currently, most aquarium kits that include a light or hood with a light do not offer LED lights. Popular combination units, such as the Eclipse systems, are only offered with standard fluorescent light bulbs. Likewise, most light fixtures are still offered primarily with fluorescent lights. The LED fixtures that do exist tend to be a bit more costly to purchase upfront, but you'll more than make up for it over time in energy savings as well as bulb replacement costs.
The other primary weakness is in the area of planted aquariums. Currently, most LED light fixtures are only suited for low to medium lighting needs. That will do nicely for virtually all fish and for a number of plants. For plants that have high light needs, however, there are no good LED lighting options right now. That is quite likely to change in the near future, as the LED field is rapidly expanding with new products. Most experts agree the future is bright for LEDs.
Not as available as other lighting options.
Initial cost is higher.
Not suitable for high lighting needs.