i grow in a attis with the same measurements as you are talking aboutand i use a 1000 watt hps and a heater to keep the temp up at the moment i dont know if you are in a warm climate as i am in ireland so the temps are low here at the moment so heres a link to a light thats getting good things said about it .

http://www.progrow.co.uk/acatalog/fl...t_systems.html
postmandave Reviewed by postmandave on . New Grow (Second time growing) I am currently preparing my 2nd grow and need much advice. I am looking to grow between 9 and 12 plants and am starting with unknown seeds, hence the range since I dont know how many will be males. I am growing in an unfinished, unused, unheated, nonlighted attic. When I found the area I instantly realized the insane amount of potential. For this first grow in this area however I plan to start small, however the area does have the potential to grow hundreds of full-sized plants. My aim Rating: 5