say you had a 1000 watt light sealed and cooled, good room temp and you could actually get the glass lets say within 1 inch from the light. i know you need to move the light as the plant grows but how far away would you actually want it in all the different stages from clone through flower. farther away in veg and closer and closer as flowering continues then back it off the last couple weeks?
this is a good question. I can get my 400w right down on mine as well without heat being a direct issue. The issue becomes how concentrated the light is in the middle. I get some heat stress in the center, not even at the tops. That might have something to do with the reflector? Edit: I keep mine currently about 4" the top of the tallest plants.
You want to keep your light a couple feet away from your seedlings and clones so you don't cook them. After that, put your light as close as you can without burning your plant Put your hand at the top of your plant and lower your light down until the back of your hand feels hot. That's what I've heard as a good indicator.
He's asking what if you could control the heat to be able to get the plant within 1 inch... I don't know if you could cool a 1kw to that extent. If you can, then you would need to watch for light bleaching or light burn. It's difficult but not impossible to give MJ plants too much light, I think 1 inch from a 1kw HID would do it. If you can get a 1kw within 6-12 inches of the plant you will be in great shape, no need to try to push it beyond that.
thx for the responses. they have had a few days of it being 3 feet away. i think its time to move it closer