400 Watt Cool Tube Distance???

I have a 400 watt MH running inside a 6" x 30" Cool Tube connected to a 240 cfm inline fan. I am growing in a 3' x 3' 7' grow tent temps are at 24 - 80 F.

I was wondering how far can i put my cool tube away from my plant. When i touch the glass it's cool to the touch but if i hold my hand under the light the light itself feels like it could burn my plants not the heat from the bulb. Some people say putting the tube a inch above your plants is okay and others say that you should keep it at 8 inches away.

You put your hand at the top of your canopy if it feels hot you should raise it a little at a time until you don't feel the heat any more. This is how I do it and it seems to be a favorite method with many growers.

That will probably be too much light for that seedling you should hook up a couple of cfls over that seedling till it gets a little bigger otherwise you are probably going to kill that seedling.

Dr. Skunk Bud said:

That will probably be too much light for that seedling you should hook up a couple of cfls over that seedling till it gets a little bigger otherwise you are probably going to kill that seedling.

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You should be more specific, now I have no idea if you're talking about that seedling or not

No that seedling is 3 weeks old now nice and big

joshua6651 said:

I have a 400 watt MH running inside a 6" x 30" Cool Tube connected to a 240 cfm inline fan. I am growing in a 3' x 3' 7' grow tent temps are at 24 - 80 F.

I was wondering how far can i put my cool tube away from my plant. When i touch the glass it's cool to the touch but if i hold my hand under the light the light itself feels like it could burn my plants not the heat from the bulb. Some people say putting the tube a inch above your plants is okay and others say that you should keep it at 8 inches away.
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An inch is too close. You will see bleaching that close IME.

...as in I stupidly did this ;0) ...never an inch though.

18" is a ballpark answer, but the hand method works in all cases.

Good luck,

JD

Personally if I was just starting one plant. I would hang a 6500k cfl for 2 weeks. Then switch on the HID, but hey that's just me. To answer the question. Keep the light higher for the first week. At least until you have have some good primary leafs.

this moron ^^ has been reported (not niigataOp if post gets deleted) use this as a guide, Javas right about bleaching I got bleaching at 5-6 inches with 400 cooltube. I'd say about 8 inches + dependant on temps obviously

this moron ^^ has been reported (not niigataOp if post gets deleted)

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LOL....you gotta add that last bit. Good move.

I left it out...and was left looking as if I had said

"More Entrails For The Wolves"

to a normal person. LMAO. It was cool. People knew.

Onward and upward,

JD

P.S. No, that was another time...I went all Yoda...
"Spam, you are". LOL!

You had me scared though. I was heavily medicating trying to post that last night. Went in search of that same chart. Needless to say got distracted. Anyways use the chart and the hand method in combination with each other and you can't go wrong. Just remember that seedlings are more sensitive to light and heat.

Another thing to think about is the temp swings. 24-80F is a big swing. I have to assume its 24C but if you are getting that big of a swing. Your end up with some nice purple bud.