I have the Hydrofarm 4'.5" x 4'.5" and i can tell you that heat is a major factor without a cooling reflector and you need extra fans pulling fresh air in! not to mention your plants need all the air they can get....down here in the south....1000w would be over kill and not woth the trouble nor the extra $20-$30 on your bill....stick with the 600w and consider some cfls underneath if you want to feed the bottom of your plants....you'll be happy....a good strain, nutes, and good hydro setup, you'll be impressed in that hut