Quote Originally Posted by Moose101
Could have sworn I read somewhere that you need 7% of your total grow lights to be blue, anymore wouldn't do anything.
Yes, ive seen some studies (none specifically about cannabis) wich concludes that a minimun of 6% of micromols of photons blues is enough for some plants species. And, in general, between 6% and 12%.

Other studies concludes that the blue requeriments are absolute, rather than a percentage of total. Usually, a minimun of 30uE of blue light per sq meter for healthy grow, and about 40uE for healthy growth with short internodal spaces (the difference between a generic 400wHPS lamp in one sq meter against an enhanced blue 400w HPS bulb; with the diference between leds and HPSs consisting in a HPS blue emision near 500nm, very less effective than a 450nm blue led).

The problem is only see the 6% figure. It refers to percentage of total micromols of photons per second (uE), not a emitted watt percentage. Blue photons carry a lot more energy than reds, so a 6% of uE means near 20% of emitted watts, and like blue leds are more inefficients, problably means near 35 or 40% of the total installed led watts.

Probably the way to go is having blue arrays wich emitts 40uE/m2, and go adding more and more red light as plants grow, anf forgot the % of blue light.