For flowering I use 72 watt bulbs, they sell em at Home Depot, huge CFL's, I use six hanging from the top with reflector and for side lighting I have at least six 42 watt CFL's, plus some random 23 watts that I move around the plants. I use all of those for two or three plants max. So, 72x6=430 watts on top with reflector and 42x6=250 watts side lighting. This is in a small 3x3x5 closet I built. Heat becomes an issue at times, so I crank up my carbon filter/fan to max and sometimes turn off smaller lights (23 watters). So to summarize, approximately 680 watts of cfl's at 2600k for flowering, temps around 80 F, humidity around 50-60%, sometimes gets higher after watering. The more watts, the higher the heat, it's a trade-off. Good luck, hope this helps. Peace!