Quote Originally Posted by bongerstonerd00d
I have done a great deal of reading, and I have yet to see where it was suggested that you have 10,000 lumens per sq. ft. That would mean to have optimal growing conditions you would need 1000 watt HPS in a grow cabinet that measures 4 x 3.5 feet, roughly. Damn, how the hell would you keep that cool? If 10K per sq. ft. is the number, then all the hydroponic sites are dead wrong on their suggested coverage area per light, and advertising falsely. I wish some of the other experienced growers would shed some further "ight" on this (no pun intended).

I am just a noob idiot, but I love to read.

peace all,
b0nger
Well, if you're looking to produce optimum growing conditions, you'll follow Mother Nature's example with the Earth-Sun distance. I myself use several thousand lumens per square foot, and I can still see room for improvement.

Cannabis requires a lot of light -- as much as we can provide. This means that we'd need to replicate the environmental conditions seen outdoors -- 10,000 footcandles/lumens per square foot on a sunny day. Three thousand, like what is suggested on some cannabis cultivation sites, is minimal and typically produces lower yielding plants of sometimes questionable quality [ i.e.: less dense buds ].

And a 4' x 4' SCRoG/SoG space under a 1000w HPS/MH isn't unheard of, even in cabinet grows. The key is ventilation, which includes good intake and definitely good exhaust, especially around the light.

Air-cooled hoods, anyone?