Yeah, as it was said up there, it doesnt matter what so ever, as long as the light isnt burning your plants you can have it as close as you like.

I'd also recommend a HPS conversion bulb, the yeild will be much higher.
LIP Reviewed by LIP on . How close should I get? I've had my plant, which is about 11 1/2''- 12'', 18 inches away from my light. My light is a 400w Agrosun Gold Metal Halide. My friend who I purchased the light from told me that 18" is far away for such low watts, and that 18" was for a 1000w system. What shouuld I do? Rating: 5