Blurb of mien from another thread. Should apply to a 400w hps as well
I was pulling an oz a week with 388w of CFL here - First CFL Grow - Help appreciated
Keep them small! CFLs/lower wattage HIDs don't do nearly as well with large plants unless you keep a clean scrog or LST. I started flowering at this size -
Dropping bulb between plants maximizes plant absorption without the loss of restrike like you would have with a reflector. I tried to cover the canopy in smaller bulbs and submerge larger bulbs between plants.
I would yield ~ 1oz per plant. With 6 in full flower at a time and two others just rotating into the flower box I was able to harvest a plant per week.
This took place in a 2x3x3.5' area of a small closet.
