Yep, LEDs can easily hit the 10-20k range and even higher.
Spectrum and Kelvin are closely related. Light in the 420nm (nano meter) range is what's called "actinic" lighting. Those are the very blue, to almost purple lights you se on many reef tanks. Light in those wavelengths tends to bring out the natural flouresence of many corals. While
actinic light is not strictly necessary, many people prefer to use primary lighting in the 10,000K range to get good growth, and use
actinic lighting to offset the yellowish cast bulbs in that range can produce.
You surely don't want all of your lighting in the
actinic range. While corals will use some light in that range for photosynthesis, it's mosty for our own personal aesthetics.
For example, my main lighting is 2 400 watt
metal halide lamps with 10,000k bulbs, and 2 54 watt
T5 flourescent tubes that are
actinic because I find the overall effect pleasing. I could certainly go without the
actinic lights and the coral wouldn't care a bit.
What kind of lighting are you considering? Flourescent, LED,
metal halides? What sixe tank are you looking to light and what would you like to keep in it?
BTW, Reef Monkey is just my title around here
I go by Phurst
