Recommend height for MH lighting

[Kevin Spencer]

i have some seedlings starting i was reading that having ur mh light to low will fry ur seedlings and then having it to high causes it to stretch , from what ive read 5 feet is the norm, but i was wondering what u guys thought about 4 feet high for the seedlings and im not to sure after they start growing like during veg and bloom how high i should keep it. thx guys, my average temp is between 72-78 night and day so any help or suggestions would be nice, i know i gotta test it for my self as well so but anyway help is generously accepted. oh btw i got a 400 watter mh, going to get another in a room with 2.5ft wide, 6 tall and 7 long

Kevin Spencer Reviewed by Kevin Spencer on 04-06-2006. Recommend height for MH lighting i have some seedlings starting i was reading that having ur mh light to low will fry ur seedlings and then having it to high causes it to stretch , from what ive read 5 feet is the norm, but i was wondering what u guys thought about 4 feet high for the seedlings and im not to sure after they start growing like during veg and bloom how high i should keep it. thx guys, my average temp is between 72-78 night and day so any help or suggestions would be nice, i know i gotta test it for my self as Rating: 5

[dreadydrug]

i've had mine about 2ft with a fan on 24/7. if you have some sort of cooling system then you can get it much lower & your plants will be more compact. another advantage of a cooling system (in a grow room) is that it also constantly has fresh air in the room so your plants have always got fresh CO2.

[dreadydrug]

ah just realised u had a 400W. i'd keep it a little further away. a good way to test would be to pic a leaf (similar to the texture of a cannabis leaf) & put that under the light, if it just dry's out it'll prob be ok, but if it burns then it's not!

[LIP]

About 2 1/2 foot should be ok, but if it burns your hand its too close.

[latewood]

4 foot would be a safe distance, but could stretch the seedlings making them weak-legged...

like stated in other replies...get light as close as possible to canopy with a constant fan blowing between the light and the canopy, without melting them...a good test. After you set your light, let's say, 18" above the canopy...place your hand right at the top of your canopy, and if your hand does not start to burn after a minute; You are OK. check often, or even back your lamp off a 2-4" if you "feel" that your lamp is too close. hope this helps. lw

Make sure you have a nice little fan that blows cool air between the lamp and the plants.

[Kevin Spencer]

but as uve probably guessed an anwser leads to another question from, what would u think would be good for me, i bought 2 mh ballasts and was thinkin of setting um up in there, well there already set up i just got the one going right now, but anyways yea would it be worth it to add another one into there, ive got a couple ventilation ideas but would u guys think that would be to hot or is it even nessasary in a space 2.5ft wide, i remesured the height and ive only got 5 and a lil bit to work with but its 6 feet long
thx

[BlueDragonSmoke]

<-----<<< is NO pro , but what i would do is go to walmart buy a flou. light , the one that holds 2 , 4 foot bulbs there like $14 and buy to bulbs set it up and now you have a cloneing light and a starter light for seedlings...way less electric than that h.i.d. light ... put the 4 foot light a inch or less to the seedling tops on 24/7 for 1.5 - 2 weeks then put them under the H.I.D. and put the light like a foot away with good air movement I have mine 3 inches from my 400 mh and its not in a cool tube....lol an inch and a half away from my bare bulb it is only warm .... You have to keep fresh cool air comming in your box , and you have to get it sucked out just as fast .....pease

[latewood]

the footprint for a 400w h.i.d. is 4x4'. 2 would work great.
fluoros work well as stated above, but you already have 2 400w so go for it. Just make sure that you have good exhaust to keep a healthy airflow; And a good fan across top of canopy.

footprints by size.
250w 2x3'
400w-4x4'
600w-6x6'
1000w-8x8'

[Kevin Spencer]

hey thx guys, so latewood, u think its not a bad idea for me to use both 400w from what u posted im pretty sure, so thats cool but i was wondering, right now the temp is about 74-78 F depending on time of day and i havent hooked up the other one, so i aint to sure yet, but eventually when they get big enough im going to buy a floro and clone some, but for now, im just vegging, but yea to my question, i was think of tapping into my attic for ventilation, i was going to buy a professional fan but they run from 150-250$ so i was wonder if i could construct my own fan with a box and filter with just a regular house fan blowin to the attic or would that not be good" or i was think just tapping into the wall? im going to test the temp with both running. thanks again u guys u are loads of fucking help
thx

[Kevin Spencer]

hey thx guys, so latewood, u think its not a bad idea for me to use both 400w from what u posted im pretty sure, so thats cool but i was wondering, right now the temp is about 74-78 F depending on time of day and i havent hooked up the other one, so i aint to sure yet, but eventually when they get big enough im going to buy a floro and clone some, but for now, im just vegging, but yea to my question, i was think of tapping into my attic for ventilation, i was going to buy a professional fan but they run from 150-250$ so i was wonder if i could construct my own fan with a box and filter with just a regular house fan blowin to the attic or would that not be good" or i was think just tapping into the wall? im going to test the temp with both running. thanks again u guys u are loads of fucking help
thx