ok if i build a growbox that is 4 foot high and 3 foot by 3 foot would a 400 watt with a cool tube be enough of a footprint?
If you use a 400 watter then you won't have enough grow space,given the distace the plants have to be from the light, about 12".
take into considerationt that however tall you let your plant grow during veg, in flowering it will double that (normally)