a medical grower I know uses 1000w metal halide with 600w hps in flower in one large cooled hood. the metal halide ALSO puts out UV radiation, which the plants LOVE in flower. It's what really develops the trichs.

red develops tight buds
UVB develops trichomes

I single plant scrog and flower 3 at a time under 6 4' red T5s plus 2 26w CFL 10% UVB reptile bulbs and a 30" 10% t-10 tube. All in a 5'5 x 26" closet. I know I don't have enough red, my buds are looser than I'd like, but my trichome production is really good.
MdmPele Reviewed by MdmPele on . Question About Optimal Light Spectrum I received an AgroMax 400 watt, 55,000 lumen output bulb with ballast and reflector. I'm using it to replace a fixture with six 24 watt, 1600 lumen, 2700K spectrum CFLs. I also have two side fixtures with 10 2700k CFLs each. The HPS light I just got is designed to output 30% additional blue light (according to the box and the website). What I've been reading is that red spectrum light is better for the flowering stage and blue spectrum is better for the vegetative stage. I'm Rating: 5