Ere is the major benefits brought by LED to the aquarium:

1, metal halide bulbs emit UV radiation and need a UV shield to protect the corals (the corals may bleach with excessive UV). Hardly any UV radiation comes from LED's. Four to one for LED's.

2, The glitter lines produced by a metal halide bulb are very attractive and assist in making the captive reef appear more natural. LED's also produce glitter lines and create the same natural lighting view.

3, The LED array has controls that will allow the light output to be adjusted for full sunlight, cloudy days, daylight, sunset or moonlight. The LED bulbs can be dimmed from maximum output to zero output.

4, A big problem with metal halides is the heat output. The radiated heat can and does warm up aquarium seawater. While LED's heat output is much lower. Also, the LED unit, however, has been shown to direct heat away from the aquarium seawater. This is done by means of fans. The seawater is not heated up.

5. metal halide bulbs need to be changed at two years (or less), to avoid light intensity reduction and spectrum shift. While The LED lights can run for up to 50000 hours. Generally the 'lights on' period for a reef aquarium is 12 hours. This means the LED's can run for 11 years!