what lighting spectrum?

[StirCrazy]

Originally Posted by marlboro man

the link you provided said 6,700K provided the best coral growth.
So I guess I will use a tube of 10,000k and another at 6,700 K then.

this is a kinda of a misconception and a trade off. yes 6700K will give you better growth than a 10 K but the color of your corals will suffer. now having said that if lighting was the only thing that contributed to coral growth and color this post would be over, you also have dissolved nutrients, chemical make up of the water (PH, Alk, Ca, Na ect...) location in the tank relative to the light, and so on.

I have seen tanks with 20000K bulbs show as much growth as a tank with Iwasaki's so lighting is one of the building blocks but not everything. pick the color that you are most happy with looking at. Usually a 10K MH with VHO actinic supplementation is very appealing but some people like more blue and go with radium style bulbs and some like less blue (why I am not sure ) and go with the 6500K type bulb. I personally use 10K bulbs with two 94watt VHO Actinic.