i have a 600 watt hps light but i am limited on space when i am walking now its hanging horozontal but i want to hang it vertical because the exhust vent that i am using the room is only 6 ft by 6ft with the fan and the exhuast hose its at least 4 ft long if i hang it vertical it would eliminate several of my problems my room is home made but i have wrapped in mylar so i will have plenty of reflection from all sides plus hanging horozontal i have to keep moving my plants so they get ample light to all sides of the plant