Light distance?

I have seen a couple different theories about the distance you should have a grow light from the canopy. Of course the instructions that come with a grow light always have their set parameters for the different light heights for the different stages of growth. I was following the instrauctions and it was working fine. But when I finally got my 2x4 grow tent, I started having light burn issues when I followed the heights according to the directions. It wasn’t because of the heat, my viperspectea P600 lights have very effective heat sinks and I have two fans in the tent, keeping the lights cool to the touch. I then stumbled upon a video where a man said that it is better to have a light higher up when working in a Mylar tent, because it allows the light to bounce around more to hit the plant more evenly. This made some sense to me so that is what I have done. I have put the lights up as high as possible and turned the dimmer to 100%. I am not experiencing light burn anymore, but now I am questioning myself. I would like to clear this up for myself. Is it more efficient to have the light as close as possible? Or is the theory of “higher light=more even light on the plant” a better route to take? I appreciate any input, I am still relatively new at this. Thank you!

If it was light burn, then yes raise or dim, maybe both. With LED it is usually the intensity of light not actual heat that causes issues. Some strains react negatively to that intensity

If you see too much stretch ,lower light!

Yes, because you have it right on the plants you can turn it way down thus using less electricity! This can cause other issues until you get used to using this type of light.

True, it spreads out the coverage= less PPFD(intensity, more or less) at every point on the canopy. Welcome to ILGM forum, lots of info here!
You can get some ones attention by putting @ in front of screen name like thi @Gleathers

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People tend to prefer 2 lights rather then 1 in rectangular spaces ( or a light with a big spacer like the hlg 260 xl) for edge coverage and I literally couldn’t even use my 260 xl for seedlings without the dimmer (30 in at 25% dimmer seems good so far) but for early growth in a wider tent with 1 light higher is better but less efficient use of power

I have two lights! That makes sense to me which is why I chose to get two lights. Each of my Viparspectra p600 cover a 2.5’ x 2.5’ for veg and 2’x2’ flower area. So I thought that worked out perfectly with my rectangular shaped 2x4 tent. Thank you for the input!

Sorry for resurrecting this zombie thread but trying to fully wrap my head around PAR/PPFD and DLI.

Light distance vs PPFD are they the same? What I’m asking I guess is PPFD at the canopy more important than distance of light from canopy or is it the same? What I mean is if I set the PPFD at the canopy where it needs to be for that stage of growth does the distance of light mean anything aside from the potential for more heat the closer the light gets. My thinking is as long as the PPFD at the canopy is where it should be the distance of lights has no bearing.

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This might help
Start using DLI - Indoor Growing / Lighting - I Love Growing Marijuana Forum



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