Shango, I'm assuming you're using florescents. From what I know the answer is both. After about a year the wavelength changes and the wattage curve begins to drop relatively quickly. Having electronic ballast helps to a point. Clay Anderson On Friday, November 14, 2008, at 02:41 PM, gsas-member-request@thekrib.com wrote: > I was suspicious of the bulb life but this is new to me. Does it just > decrease the wattage experienced by the plants OR is it a change in > wave > frequency OR both or More? _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member