There are a few things I need cleared up. Do I have this right? Lumen refers to only the visible spectrum? I thought lumen referred to the brightness of all light. So, how do you refer to the light intensity of the non-visible spectrum? Also, don't plants mainly use light within the visible spectrum? I thought the visible spectrum was between 380nm and 760nm. It makes sense to me that the brightness of a light source would determine the amount of energy or photons given off by that particular light source. I know it would take some precise measuring, but if a 6500K light produces let say 15,000 lumens and a PAR specific light produced only 1,000 lumens, I would think it would be safe to assume that the 6500K light would grow plants better due to the higher lumen factor.
Plants mainly use light within the visible spectrum as far as I can tell.
Wiki:
Electromagnetic radiation with a
wavelength between 380
nm and 760 nm (790400 terahertz) is detected by the human eye and perceived as visible light. Other wavelengths, especially near infrared (longer than 760 nm) and ultraviolet (shorter than 380 nm) are also sometimes referred to as light, especially when the visibility to humans is not relevant.
P.S.
Wouldn't it be possible for a 6500K light bulb to have more PAR than another 6500K bulb? I thought the Kelvin representation was just an average of color temperature. So wouldn't it be possible for a 6500K bulb to have more blue and red light than let say green or yellow and it just happens to average out at the 6500K zone? For example, when I was at the aquatics store the other day I checked out some lights they had glowing in a few different aquariums. In one aquarium they had the Coralife Nutrigrow lights and in another they had the Zoomed Ultrasun lights. The Nutrigrows had far more pink and the Ultrasuns had far more blue. This was detectable by looking at them. The color difference was obvious, yet they are both listed as 6500K!!