| Lumens are usually used to rate the amount of light production a lamp is capable of producing - keep in mind that this disintegrates with time/age and as the lamp becomes dirty. Footcandles have to do with the intensity of the light striking the measuring source (such as your plant's leaves) at any given point. To maximize utilization of lumens you want to direct as high of a percentage of the output as possible at your plant(s) - this is done by keeping them close and by directing as much as the light output as possible towards the plant through shielding/fixtures. |