i'll try to make the driver page more explicit.
trying to be polite here, but its kind of not up for debate. Youre the only person who advises 400, every other person on this site would say 600-1200. and there is plenty of science to back that up. But there are other threads for that. im all for 400+ on the bottoms but top canopy really should have 600+
Being polite is why I said it was up for debate.
I totally agree that plants will accept more light but that it doesn't mean they will use it. That gives lots of room before ill effects of too much light start to appear. As long as you are within that range then increases in light from a singular top source provides a benefit by bringing lower regions of the plant will into the optimal range.
Producing as efficiently as possible also means making sure that as much of the light produced by the light source as possible is used by the plant. If photosynthesis maxes out at 400 umols then we know that should be our target for all areas of the plant where photosynthesis occurs. You can get there by pounding the plant from the top with excessive amounts resulting in >600 umols at the canopy or by dispersing discrete light sources around the plant.
With the latter approach you can get higher yields using the same amount of light. That really is the point. I don't think anyone disagrees that using multiple light sources is much better than a single one for most indoor growing.
