I'm with psteve...dual 600s are great. You actually aren't generating any more light with two 600w bulbs as opposed to a single 1000w...but your plants will be closer to the bulbs. If you've got a good sized grow space like you do, it's easy to forget how fast lumen output disappears with distance. When you've got two bulbs, plants are nearer to at least one of the bulbs than they are with a single bulb and reflector. So whatever light you would â??loseâ? from using a 600w vs. a 1000w would be gained by having your plants a few inches closer. Those few inches mean a lot!