I've heard and read that 1000 watts is plenty for a 4 X4 area for flower ( 16 plants ), I thought doing 2000 watts would sort of be overkill. I've also heard that the more light the better no matter what Jorge Cervantes says and some people like yourself will usually only put 4 plants max under one 1000 watt. It's surprising to me that no one encounters cold issues during the winter, it could be killing my yield!