in all actuality, they say anything over 40w per sq. ft. is over kill, and your wasting energy = money. But I still do about 60-70w per sq. ft. but only during flowering. From my experiences it hasn't done anything in veg. but it makes a world of difference in flowering. You should roughly double the amount of light from veg to flower. I would say that 12 CFL's is the most you would need. Well actually I use a mixture of HID, CFLs and Flouro fixtures. But in all honesty, watts, lumens, lux its all an un-accurate way of measuring efficency and effectiveness, PAR is the way to go, its what the plant is really getting not what we see.