+REP How far to have the light: 250w MH air cooled hood, on SEEDLINGS

Sr. Verde

Sr. Verde

Well-Known Member
Hey guys!

Not my first grow, but my first HID light grow. :mrgreen:

I'm wondering how far to have the light from seedlings. I know it's farther, but how much farther? Is it a matter of light intensity, or heat? :dunce:

That and about 6 inches from them, when they get a little bigger with some fan leaves yeah?





This is about as low as my hood goesbongsmilie:

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It is usually a matter of both light intesity and heat but more of the first. I veg and and start seeds under flouros as I have tried using HID lights for both and just have had problems not so much with vegging but always with starting seeds. I would almost always get dampening off or they would burn up. I know it can be done but I would suggest starting the light about a foot from the seedlings and gradually lowering the light daily to within six inches but a four foot shop light with two flouro bulbs is cheap and I would just start my seeds with that and than gradually introduce the HID light to them when they get a couple sets of true leaves on them that way they will be strong enough to deal with the high intesity of the HID light. But either way you do it just start the light about a foot from the plants and gradually lower it about an inch over the course of six days until the light is within six inches of the plant that way the plants at least can get gradually used to the high intesity light of the HID instead of just blinding them with light. I know there are different oppinions on this but I have found that this works for me and I have very minimal stretching.
 
varscience21 said:
It is usually a matter of both light intesity and heat but more of the first. I veg and and start seeds under flouros as I have tried using HID lights for both and just have had problems not so much with vegging but always with starting seeds. I would almost always get dampening off or they would burn up. I know it can be done but I would suggest starting the light about a foot from the seedlings and gradually lowering the light daily to within six inches but a four foot shop light with two flouro bulbs is cheap and I would just start my seeds with that and than gradually introduce the HID light to them when they get a couple sets of true leaves on them that way they will be strong enough to deal with the high intesity of the HID light. But either way you do it just start the light about a foot from the plants and gradually lower it about an inch over the course of six days until the light is within six inches of the plant that way the plants at least can get gradually used to the high intesity light of the HID instead of just blinding them with light. I know there are different oppinions on this but I have found that this works for me and I have very minimal stretching.
Click to expand...

Great answer man :D

Yeah it was a BITCH to get everything in the tent just perfect, and all that shit cost a LOT of money... so I'm just barely getting by right now.. So I'm going to use the MH for the seedlings. Maybe t5 in the future. Probably like you said do a foot, or a foot and a half if they look stressed.. The MH is super bright, so I don't think a lot of stretching will occur even if it's a foot and a half a way

ooohhh I'm excited 8)
 
bro start your seeds under your old cfls and move them under the 250 later...but air cooled should be GREAT for a close distance between the two. i used my 250 only after the popped the second node...
 
I always started my seeds under T5's or flouro's but I purchased some seeds from sannies and read how he said to start them so I followed his directions. Heat is the big issue, I have 17 seeds I started under a 400 and the light is 18" away and they are still stretching a bit. Seeds outside have the sun for light and they don't have issues? IMHO
 
I run 250 and from seed I kept the light 10" for the first 10 days or so. Not in a tent. A closet if that matters. I just went off the "if your hand is comfortable" theory for light and doubled the distance. Worked for me...
 
Dick Moser said:
bro start your seeds under your old cfls and move them under the 250 later...but air cooled should be GREAT for a close distance between the two. i used my 250 only after the popped the second node...
Click to expand...
I don't have my cfls anymore.. I gave them away. :lol: plus ughh I don't even want to look at those things! Such a hassle.

woodsmaneh! said:
I always started my seeds under T5's or flouro's but I purchased some seeds from sannies and read how he said to start them so I followed his directions. Heat is the big issue, I have 17 seeds I started under a 400 and the light is 18" away and they are still stretching a bit. Seeds outside have the sun for light and they don't have issues? IMHO
Click to expand...

Yeah I feel that. I'll get a T5 for the next grow for sure. I did the heat test after an hour of running today, I can practically have my hand an inch away with NO irritation! :D I have tempered glass on the hood, I hear that helps with the heat!

auldone said:
I run 250 and from seed I kept the light 10" for the first 10 days or so. Not in a tent. A closet if that matters. I just went off the "if your hand is comfortable" theory for light and doubled the distance. Worked for me...
Click to expand...

Good to hear! I'll probably do the same, keep it around a foot to be safe, and look out for the stretch!

+rep to you all
 
i feel so dumb...i didnt mean air cooled i ment hooded...damn my bad my bad...with a HOODED AND GLASSED 250 you should have great chances of getting under a foot of distance. there i feel better
 
auldone said:
I run 250 and from seed I kept the light 10" for the first 10 days or so. Not in a tent. A closet if that matters. I just went off the "if your hand is comfortable" theory for light and doubled the distance. Worked for me...
Click to expand...

I did the exact same.
Good luck with your grow!
 
Air cooled... hooded?

What am I missing here? What's the difference?

Again, noob to HID/HVAC... learning fast though :bongsmilie:

Again, to clarify the setup: inline fan pulling air through the hood...


also I'm sorry I'm out of rep for now! PM me if I missed you, and I will surely get you tomorrow...

about 30 hours into germination... 3 of 4 tangerine dreams have cracked open! Going into the soil tonight hopefully!
 
Air cooled is like what you have set up. An inline fan either pulling the air and displacing it, or blowing on the light. Just having a hood does not mean that you need to air cool it, ie: a huge grow roow or just a room where you have the temp under control.

That is awesome that 3 out of the 4 are germ'd and the fun begins.

As for the HID for seedlings. I just did a batch of white widow, I know its a different strain, and three of the five burned up. One pop'd with the cotyledon already burnt and the other one came up just a stem. NO NOTHING!! I would recommend just like everyone else and start your seedlings out under fluro's and then ease them under the HID.

I know you already got rid of everything except your new HID so keep it at least 1 foot away until you can start noticing different patterns with your girls.

GOOD LUCK man.
 
use a little hood made with some clear plastic of really any kind to keep a nice humid environment and you really shouldnt have any problems
 
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