A 1000W HID would be perfect for that size room, as long as you can keep things well ventilated and cool. But if you're leaning between the 400 and the 600, I'd go with the 600 too. That's like an extra 15,000 lumens or so, and the plants will take as much light as they can get. Remember to spend about as much on ventilation as you would on your light, which will alleviate a lot of problems right off the bat. Good luck!
Mr. Clandestine Reviewed by Mr. Clandestine on . 400w HPS vs. 600w If I'm gonna have a grow room approx. 4W x 4L x 6H, and perhaps 2-4 plants, would a 400w or 600w HPS be better? I don't wanna buy a 400w and then always be wondering if I should have gotten the 600w... Rating: 5