Light Height Question

How far should I have MH and HPS lighting during all stages of growth. For example should I always keep the lights about one foot from plant tops? I have a 400 watt convertible setup. My first grow I kept my lights about 12 inches from the tops of my plants and had problems with stretching especially during the first week of flowering. How can I prevent this? Should I keep the lights 2 feet from the plants?

lower a inch a day watch the way your plant reacts to the light (leafs curling up)

adjust light when plant grow....
hope this helps

i keep my 2 1000watt lights pretty much as close as i can, to where its not uncomfortable for my hand. but hey, they're gonna stretch like hell when you flip the switch to 12/12