Hey Biggee I got a 400 watt MH/HPS (Metal Halide for veg and High Pressure Sodium for flowering) in my closet. I'm not sure about the exact size of the closet, its just a standard size one I can fit about 3 plants in it. The only type of air flow I got in there is a fan and the hottest Iv'e seen it get was about 85 degrees and thats when the doors are completely closed. When the doors are cracked a little temps are between 70-80 degrees.No way to circulate the air. Just the fans. I was thinking a 250 watt hps would be pushing it because of lack of airflow
so I just figured a 150 watt hps would be good? IDK if you say a 400 I may just try that.