Natural sunlight at the equator at noon is 5000k when the equator is pretty much closest to the sun. As you move further north or south the colour temp changes. 6700k is daylight deluxe as sylvania I think calls it. Chroma 50s were probably (emphisis on probably) one of the first true daylight tubes, at 5000k it is a tri phosphor meaning it contained red/blue/yellow phosphors. Don't forget, what is rated at 10,000 by one company may appear just like a 14,000k that another company puts out. As was said, 6500/6700 is great for coral growth but it doesn't always look as appealing to our eyes.
Doug
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