LED aquarium lights from twilightgroups

  The use of LEDs as a practical lighting technology is very recent, but there are already many different aquarium units on the market. The attractions of LED  aquarium light for marine and reef aquarium use are high efficiency, low power consumption, minimal heat transfer to the water, very long life (around 10 years is claimed for most units) with no need for replacement of bulbs, and the potential for sophisticated electronic control of intensity and color.
The market in aquarium LED units is developing fast, reflecting improvements in LEDs themselves and in control circuitry. While early units tended to be suitable only for nano aquariums, with relatively poor light output (compared to metal halides, at least), much more powerful units have since become available, and it's probably fair to say that these units are genuinely equivalent to high-powered metal halides.
So are there downsides to LED  aquarium light ? There is one big one: the purchase price. While lifetime costs are probably lower than for other types of lighting (due to the low power consumption, long life, and lack of need for bulb replacements), the initial investment required (especially when fitting out a large tank) is very high, although prices are gradually falling. Also, in such a rapidly developing market, it can be difficult to select a unit, especially as units can be very different in intensity, color, controls, and the spread of light they produce. The latter is an important factor; units vary a lot in their configuration of individual LEDs, each of which acts as a point-source of light. Some units use lenses to focus the light into a tight beam; others spread the light over a wide area. Which to choose depends very much on the design of the aquarium. The visual effect of LED lighting, while always tending towards the dramatic, also varies greatly among units.
 Before leaving the topic of LED reef lights , it is worth noting that, at least for less-critical applications, it is possible to use general-purpose units to light aquariums. There is a wide range of LED spotlights, floodlights, and other bulbs with adequate intensity and suitable color temperatures (over 6,000 K), and these can be used for aquarium lighting. These units do not have the sophisticated controls of some aquarium lighting systems but are typically much less expensive and are just as energy-efficient and long-lasting.