New 400w Hps how far away?

I just bought a new 400w hps with 4-sided reflector and grow bulb that produces 55,000 lumens i was wondering since i have seedlings that just sprouted and also plants that are almost about to go into flowering how far away i should keep the hps cuz i definatley dont want to burn the Big Bud strain seedlings.....please help....

I'm fairly certain ~25-30 inches would be far enough away.

so like a little less then 2 feet would be fine and wont burn my seedlings?

well i have a 600w HPS and that fucker gets hot as hell, i just put a small fan in the room blowing over my babies and i can move the light alot closer......so you can put your light closer then 2 feet if you can keep your lil babies cool enuff, but if you dont have a fan, yeah i would say 2 feet, and keep a close eye on them, i dont know how hot a 400w gets.......

b safe start with 3 feet with seedligs always can move closer if strechin... i have a 400hps with hortiluxeye bulb.just upgraded the bulb seems alot better than just regular bulb ive found if it hot on ur hand its to close gl .

I would have to agree, be safe and start with 30 inches or so, see if they are stretching or getting too hot, move closer/farther away as needed.

get a air cooled reflector and you can maximise your grow space

i use a 400 watt for flowering plants and a few cfl's for veg. it wouldnt be expensive to get a few. recently i got a 175 watt mercury vapor for vegging. people said it wouldnt be good but i just veg with it and its fine.

the 400 watt mh i put about 8-9 inches from plant with a fan blowing at the bulb. and 2 pc fans 1 in 1 out.

i would start a room just for vegging.

thanks for all the replies.....i have fans in there blowing at what i think are my 2 first female and i have to take 1 more out which is a male i think so no shaky shaky for my girls cuz then they aint so tasty tasty. thank you elite for helping out even with some pics! definately greatful you posted ....but a 400w will put out some heat so i think i might go buy a new oscilatin fan tomro when it arrives!

the fan i have inside is a small muffin fan it is about 4 inches wide it blows across the top of the buds the other important part are the pc fans one to bring air in and one to bring air out. check this out GROWFAQ it will help you wire up some old pc fans and keep your box cooler dont be too afraid of the wiring its all low voltage.

keep an eye on the temps for a week or so then you can gradually bring your light closer.
this is what finally helped me get nice tight buds instead of sparse shitty ones

let us know how you do.

so i can make a fan from an old pc fan and a DC connector pretty easy ....but which was is positive pressure which is negative pressure. like i mean how do you make it [negative pressure] sucking out or [positive pressure] blowing air in?? but i can get this fan like you said 4" muffin from like radioshack or grainger.

the fan only blows in one direction so set-up a closed box area to work with put one fan blowing in preferably at the bottom and one fan blowing out. its that easy. you could also go with what they call a passive intake where you put a fan drawing air out only and let the air come in from various cracks and openings in your box. the trick is to have a pretty much sealed growroom this is good too because you will also be keeping your light concentrated within a small area. i think this is one of the tricky parts of indoor growing. plants grow good when you have high watts per square foot.

i use a 400 watt MH and my room size is 40"deep x 36"wide x 45" tall it was a little tricky getting the light in there and having room for plants but if you look at the pic i postd you'll see i got it horizontal thats because it has a short celing. a muffin fan blowing across the top between the light and the celing keeps from burning anything.

What distance other people are running their 400 watt lights at means squat to you,each room is different,what does mean something is canopy tempatures,you should lower ther light as close as possible without burning the plants with heat,in order to know whats what you need a thermometer & preferably a regular thermometer,not a digital because they are effected by way too many variables to be 100% accurate at all time.

Take the thermometer & hold it about 2 inches from the canopy,measure the temp,depending on the temp you now raise or lower the light until you can get the temp at the canopy to 80 degrees,you can push 85 degrees if you must but 80 degrees is a better/safer temp.

I leave a thermometer hanging from my light & keep it hung at canopy level,that way i know where my temps are at all times.

yep i found that putting light up high and working your way down best way for me now them 12" from tops i use 600w hps with fan ofcourse good luck wae your grow

well to give you a more accurate description without pics i have like a townhouse with a shed in the patio..."thats the grow room" well theres some random shit in there but mainly grow room. I can have a veg and a flower but for now i only have veg side up. the tray is 2' x 4' to give you a picture and theres 2 drainage holes on either side of the tray. there in rockwool, and hydroton. the space i grow in is about 8ft x 6.5ft x 11ft so its pretty roomy but im keeping it small. so i wont be putting the lights too low at first cuz i dont have mylar yet! omg no mylar! yes im slacking...ne wayz the fan situation i think im just going to get 2 new fans and stick one inside blow air out and one out side on top blowing air in...will post pics soon tho...