So why continue to propagate false notions? There is no flaw if we're teaching/using proven botanical science. Lumens, because it is about how humans see light adds the green spectrum, which is the least used spectrum by plants (mostly absent from the PAR spectrum) and it's presence increases lumens the most of all visible spectrums.
I'm sorry but I simply don't understand how the truth is confusing?
It is easy for the lighting companies to exaggerate their spectrum graphs and par and umol figures. They also do not include the reflector. Which can be a major factor in what light gets to the plants.
I just think (and most university tests confirm ) that lumens trump spectrum every time. HPS vs MH has shown HPS wins even in veg for years. Even with the same wattage. It's because of intensity. Or lumens.
Not that the lumen figures are accurate but they are a baseline. If you make sure you have the proper watts or lumens per share foot. The averages of lamps and reflectors will likely give you enough light for a proper harvest.
If someone is asking this kind of question. Saying plants don't see lumens is not a helpful answer without an education in photosynthetic lighting.
Which I did not need for my first successful grows.
I want to mention that the university tests remain consistent even with cmh 315's. They showed that it would still take equal wattage to get equal plant growth.
I of course know the particulars of your more advanced knowledge of lighting but the question in this particular thread was a much more simple one.
And now I have confused the hell out of the answer. So I re state.
About 48 watts from the wall per square foot will likely ensure enough light for a great harvest. As long as the bulb is the right distance for its penetration.