My space will support a grow cab that's 7ft tall x 4ft wide x 3 ft deep. I may go smaller by a foot all around though. I have a 2 400w hps lights but was thinking about selling those and using the money to buy a 600w hps. since I have not grown in a cab before I will need to set up a ventilation system. After reading several posts it sounds like many are using computer fans.