I agree...a 400 is your standard HID...and Ive seen some good bud grown with justthose. So a 600 will do you justice if you can keep it cool. Your setup sounds similar to mine.

I have a 2x18ft 2 door closet. I spilt it in half with panda film for veg and flower sides. Veg side is 400W Mh and flower is 400W HPS.

Keep it cool and you'll love your 600.
TheHerbalist Reviewed by TheHerbalist on . 600 watt hps what yield should i expect from a 600 watt hps over a 2x2 foot area? will my buds be big ones? Rating: 5