The height needed for a 400W MH light?

[tekneeqs]

What is the height required to grow in a closet when you got a 400W light and want to grow the plants up to 3feet tall? I was thinking 5 feet since you need 2 feet of space between the light and the plant and the other 3 feet are for the plants.. Please help!

[GrowinGreen23]

you have to adjust if as often as the plant grows, too low and it will burn the tips if anythign start high and work your way down

i don't think there are exact measurements

GG23

[BlueBear]

Well, you want to be able to get that light closer than 2 feet, but on top of that you will need about 6 or so inches for hood of light, about 6 to 8 inches for pots unless you do a soil bed of some type. So, approx 7 inches for hood + approx say 18 for light + approx 7 for pots, but can be smaller and 36 inches for plants. With these measurements would need almost 6 Ft. The other way would be to do a SOG, or a SCROG, but I can't forget LSTing. You could cut that plant height down to about 22 to 24 inches and that includes pots, and with good air movement or an air cooled hood you could have the light about 6 to 8 inches away. All together you could ideally get down to 36 inches, but you have to have a few bucks or some skills.
Hope that this helps some.
Adieu