Any setups with consistent results?

What is a good setup for a 400w hps/mh light? what would be the optimal size of the room, 4x4? and how many plants within? would sog produce highest yields? More plants or fewer? what is best?

I'm guessing a 400W would be good for a 4X4 space. Years ago I had 3 400W in a smaller room 8X8 and I got over 2 lbs. Look for strains that are known to be easy to grow and have good yeilds. I ran into Sweet Tooth last Jan. and can't believe how it outgrows 4 other strains. So, your yield will be detirmined somewhat by how hearty and fruitful the strain is. I've had some strains that I'll never grow again due to their being kind of fragile and weak yield.

You should be able to squeeze in 4 plants if you don't plan on them getting real bushy.

You canot say how much you will get from 1 plant as there are alot of diferent things to take into account ie temps nutes water how good are the seeds how well you look after them how much co2 how tall you let them get how long you veg the list can and will go on.

4 in there would be good, unless you want to grow 12/12 from seed, in which case you could get 12 in there....check out posters "supchaka" and "del6666"....read their journals.....

To many factors to give a straight answer..

I'd recommend hydro, though.

why are there too many factors? people are being a bit ridiculous here,

what is the best design for a 400 watt? space size and plants everything else is arbitrary

with a single 400w light i would say 3x3 space is all you can grow in. you don't want really tall plants either cause that light won't have enough penetration. i would grow 9 small plants in a square under that light. veg them for a week or two max. if you are new to growing then go with soil for now. much better chance of success.