Thanks Eric, so it sounds like color temp. (Kelvin) and wavelength are independent, if I'm hearing you correctly. 10,000k bulbs are used in the SW hobby because thats what most inverts(corals) and plant(algea) see most of in the deeper waters of the ocean. Thats not to say you cant grow 'higher' plants with blue, its just that you get better results with a "fuller" spectrum bulb. Clay A. On Thursday, October 22, 2009, at 12:00 PM, gsas-member-request@thekrib.com wrote: > We don't use wavelength directly as a measure of the bulb, because the > bulb is not emitting monochromatic (one color) light, but a spectrum of > white light across many wavelengths. The color temperature is just a > measure of the relative amounts of the different wavelengths. _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member