I am in the planning stages of my first room (second grow). The room will be 3 ft. x 5 ft. x 7 ft. tall. In regards to lighting and ventilation, would a 400 watt HPS in a cool tube with a 4 inch fan/carbon filter work or would a 600 watt with a 6 inch fan/filter be more effective? The room will be used for no more then 4 plants at a time. Is bigger (600 watt/6 inch fan) better for this set up or will I be ok with the smaller light/fan and save a few bucks? I appreciate the input. This site has been priceless so far. My first grow in a grow box is just finishing up and my new clones are vegging nicely, just waiting for their new home!