Wow, this thread is booming... And so is FootClans post count!
I didn't read a lot of the arguing either, so I may have missed a bit as well.
That is an interesting point. I see that when you purchase individual LEDs, they do give a Lumen output. Here is a
90W Cool White LED with a 3800lm rating. So it is possible to get LEDs with lumen ratings, there is even an 21200lm LED that is a hell of a lot cheaper than that cool white one! I bring that up, because it is obviously possible to measure LEDs by lumen output. It makes me wonder why that is not given by the grow light manufacturers. IMO it may be a sign of inferior product.
Now, one thing that I have always wondered when it comes to lights, is the relationship between wattage, lumens, and wavelengths. People seem to be very obsessed with wattage, which makes a bit of sense, after all it would make sense that more wattage = more light/more powerful light. But aren't lumens the actual measure of light output? Considering that an average spotting light (for deer) is about 19mil lumens, and runs off of a 12v car outlet, I'm not convinced that is true. It would seem that using lumens to compare would be more accurate, and could help with the LED issue.
Any thoughts?
EDIT:
Candlepower to Lumen Conversion