light hight

can anyone tell me what hight to keep my light from my plants ive got a 400w
sodium and have heard to keep it 2 inches from the light at all times but that seems close to me or is that right :confused:

what you want is for the light to be as close as possible without causing radiant energy burn. That is, the closer, the better. But too close, and you could have the leaves become too hot, regardless of air temperature in the room, from radiant heat energy from the light (below the visible spectrum). So go with what you have now, and check it often, if you notice that its getting the leaves too hot, move it up. Best suggestion, 2-6 inches more than that, and you'll be wasting energy by having it too far away.

Peace and Pot

ive now been told sodium it no good for starting to grow only for flowering has anyone else just grown with sodium all the way threw..

put the light abput 3inchs away from the plant then put your hand on top of the plant under the light and leave it there for a minite and see if it hot on your hand if so put the light higher.

I am currently using 2 150w hps and have them about 12-15 inches from my plant. I was going to lower them but I've noticed that the plants are growing quite well at this distance. through the next 2-3 weeks that distance will decrease drastically and I may even have to move it up a few inches. you may have to try a few hieghts but I'd say keep it further first then move closer to avoid damaging your plants.