I've had good luck with straight 40w fluorescent 48" shop lights. A bank of 4 sets (8 bulbs) produces good bud. Each bulb puts out about 3200 lumens for a total of about 25,000 lumens. I ended up with 6 good sized indica hybrids with large, tasty, sticky buds. The second generation clones produced the same results in about 75 days.