My grow room is 4' deep x 8' long x 6' tall. I will have 6 plants in it. Which wattage of HPS/MH should I use? 400w, 600w, or 1000w? I will have no A/C just room temp air pumped in and out.. Thanks for any advice..
For 6 plants you will be very happy with a 600w lamp. But that space it too big for 6 plants, make some "walls" to pen in the grow area. If you think you will be growing more plants and using more of that space in the future, though, you would be better off to think about that now and get the light that you will need in the future -- even if it's overkill now it's cheaper in the long run to buy the right light once than to buy the right light for now and then another light later.
Thanks for the quick advice toasty. Think I will go with the 1000w and just have what I need now and later. How many plants could I cram into this space? 1 per sq ft.?
You could, although you probably will want to dedicate some of that footprint to actual pathways so you can move around in there. You might also want to consider a pair of 600w instead of a single 1000w, depending on how much of that footprint you want to cover, you will spread your coverage better that way.