Light Spacing Questions

Hey there RIU!

So what is the average spacing you guys give your plants from your air-cooled HID on a 400W, 600W, and/or 1000W?

Also, how well does the glass insert in air-cooled hoods keep heat from the plants?

Thanks,

GorrillaPanic SNP

600w I was able to get about 4-5 inches from the top cola with about 2 fans and 2 inlines (push/pull configuration) in a 4x4 area (open tent though).

I recently upgraded to a 1000w midway through flowering (gift, yay me). I may be an idiot, but I closed the tent and popped a window about a cm (all air exiting the tent is filtered, I have a sensitive nose and I can't smell it anymore unless I stick my head in the tent). Right now I'm at about 8 inches (from the bulb in the air hood) and I only manage how much the window is open. If I don't monitor temp, it'll dip below 70f, but I try to maintain about 75-78.

Just my basic thoughts, the glass insert gives off an ambient heat thats nowhere near what it would be otherwise. I temporarily hooked up my old reflector hood while switching to the 1000w and the difference in temps is night and day. As far as sq ft spacing, I don't really know. I know they say 600w is about a 6x6 area, 1000w 8x8 so I'd imagine 400w -> 4x4

merkzilla said:

600w I was able to get about 4-5 inches from the top cola with about 2 fans and 2 inlines (push/pull configuration) in a 4x4 area (open tent though).

I recently upgraded to a 1000w midway through flowering (gift, yay me). I may be an idiot, but I closed the tent and popped a window about a cm (all air exiting the tent is filtered, I have a sensitive nose and I can't smell it anymore unless I stick my head in the tent). Right now I'm at about 8 inches (from the bulb in the air hood) and I only manage how much the window is open. If I don't monitor temp, it'll dip below 70f, but I try to maintain about 75-78.

Just my basic thoughts, the glass insert gives off an ambient heat thats nowhere near what it would be otherwise. I temporarily hooked up my old reflector hood while switching to the 1000w and the difference in temps is night and day. As far as sq ft spacing, I don't really know. I know they say 600w is about a 6x6 area, 1000w 8x8 so I'd imagine 400w -> 4x4

Click to expand...

Congrats on the upgrade! So about 5 inches for a 600w and 8 inches for a 1000w, with a good ventilation system from the sound of it. Do you think if you could get the lights closer to the plant without burning or heat stress, it would improve your harvest?

Bump!

Minimum:
400 = 3x3
600 = 4x4
1000 = 5x5
closer the light the better BUT heat is BAD. Check canopy with your hand or thermometer.
400 = 6"
600 = 8"
1000 = 12"
or as close as you can get without burning. Fans between lights and canopy always. Hoods trap heat above the canopy vented or not. The radiated heat is not cooled easily >.>

sir KK

you have your answer^ lol

GorrillaPanic SNP said:

Also, how well does the glass insert in air-cooled hoods keep heat from the plants?

Click to expand...

The cool tube on my 400W bulb lowers the tent temperature by 7F.

GorrillaPanic SNP said:

Congrats on the upgrade! So about 5 inches for a 600w and 8 inches for a 1000w, with a good ventilation system from the sound of it. Do you think if you could get the lights closer to the plant without burning or heat stress, it would improve your harvest?

Click to expand...

Running a 600 5" above the grow and a 1K 8" above is essentially pointless. You're curtailing the spread of the light, leaving the plants on the sides lacking full intensity, while overstaurating the few plants that get max light intensity. Pointless. One is far better off raising the 600 to 10-12" above the canopy and the 1K to ~14-18". Much better coverage and yield. FWIW, I run a number of 600s and 1Ks. Good luck.

GorrillaPanic SNP said:

Also, how well does the glass insert in air-cooled hoods keep heat from the plants?

Click to expand...

By having a a fan, that's attached to the tube, sucking the warm air out.

FWIW, unless you have a very small room, a cooltube is a fairly poor reflector. Its dispersion characteristics are very limited and it doesn't allow for full light intensity over the span of the garden. If you post some details about your setup, perhaps folks could recommend a better solution. Better, meaning you'll yield more.

Simon

if you get your lights too close to the tops of your plants it reduces the coverage of light.so if your growing 1 plant its fine,but if youre growing multiple plants you need the distance above your plants to be ideal to maximize light coverage,without losing too much intensity.also if you get your light too close it can bleach or yellow up the tops of your plants.

I see your point Simon in a large grow but I believe in small applications with proper ventilation you see a gain. I go 3'/2', 400 ,-6", no cool tube. I changed a lot at the same time manipulation, temp perfected, and saw a huge difference keeping complete canopy within 12"-18" of bulb.

https://www.rollitup.org/indoor-growing/610140-400-w-hps-distance-canopy.html sorry wrong attachment

Kush Killington said:

Minimum:
400 = 3x3
600 = 4x4
1000 = 5x5
closer the light the better BUT heat is BAD. Check canopy with your hand or thermometer.
400 = 6"
600 = 8"
1000 = 12"
or as close as you can get without burning. Fans between lights and canopy always. Hoods trap heat above the canopy vented or not. The radiated heat is not cooled easily >.>

sir KK

Click to expand...

Thanks for the info KK. When you say "Hoods trap heat above the canopy vented or not", is that because the glass panel lets heat pass through? So if you had a glass panel that reflected heat, while letting the whole spectrum pass through, you could move the light closer to the plants and improve intensity and penetration?

SimonD said:

Running a 600 5" above the grow and a 1K 8" above is essentially pointless. You're curtailing the spread of the light, leaving the plants on the sides lacking full intensity, while overstaurating the few plants that get max light intensity. Pointless. One is far better off raising the 600 to 10-12" above the canopy and the 1K to ~14-18". Much better coverage and yield. FWIW, I run a number of 600s and 1Ks. Good luck.


Simon

Click to expand...

From my recent experience with this I totally agree, I had my cooltube about 4" away but I found myself rotating the plants daily to keep growth even.

I moved it to about 12" away and they are all flourishing, even though I could hold my hand under the light and it didn't feel hot it seems the plants don't like being that close.

SimonD said:

Running a 600 5" above the grow and a 1K 8" above is essentially pointless. You're curtailing the spread of the light, leaving the plants on the sides lacking full intensity, while overstaurating the few plants that get max light intensity. Pointless. One is far better off raising the 600 to 10-12" above the canopy and the 1K to ~14-18". Much better coverage and yield. FWIW, I run a number of 600s and 1Ks. Good luck.

Click to expand...

If you have your space properly laid out with the proper amount of lights and good hoods, the loss of light spread by lowering the light a few inches should be minimal if anything.,,plus by lowering the light you get greater intensity to the plants, more penetration through the canopy and other foliage, therefore boosting the size and quality of your harvest, especially on lower branches. So the pros out-weigh the cons. The lumen output by HID bulbs decreases exponentially as you increase distance. And it is impossible to "over saturate" a plant with light, the plant will use however much light you throw at it and the more the better.

SimonD said:

By having a a fan, that's attached to the tube, sucking the warm air out.

FWIW, unless you have a very small room, a cooltube is a fairly poor reflector. Its dispersion characteristics are very limited and it doesn't allow for full light intensity over the span of the garden. If you post some details about your setup, perhaps folks could recommend a better solution. Better, meaning you'll yield more.

Click to expand...

I wasn't asking how an air-cooled hood works, i was asking how well the glass panel keeps heat from penetrating. lol I appreciate your input tho.

And I agree, cooltubes do not spread light well. Sorry for the lack of info but I am not trying to improve upon a setup, I am just doing some "peer to peer" research on light spacing due to heat transfer and how well different hood's glass panels keep heat from radiating through.

Thanks again for your input.

resinousflowers said:

if you get your lights too close to the tops of your plants it reduces the coverage of light.so if your growing 1 plant its fine,but if youre growing multiple plants you need the distance above your plants to be ideal to maximize light coverage,without losing too much intensity.also if you get your light too close it can bleach or yellow up the tops of your plants.

Click to expand...

Obviously sitting the light right on top of the plants, touching the top, would reduce coverage, but say if you could get a 1000w with a large, quality air-cooled hood within 2-3", without burning or inducing heat stress, you would get good coverage, great penetration, and amazing intensity...plus if you scrog, you wouldn't have to worry about coverage as much or the back of the plants at all, while increasing your yield.

herbbilly said:

I see your point Simon in a large grow but I believe in small applications with proper ventilation you see a gain.

Click to expand...

I agree...but even with a large garden, if you have the proper amount of lights properly spaced, loss of coverage should be minimal if any.

WeedChip said:

From my recent experience with this I totally agree, I had my cooltube about 4" away but I found myself rotating the plants daily to keep growth even.

I moved it to about 12" away and they are all flourishing, even though I could hold my hand under the light and it didn't feel hot it seems the plants don't like being that close.

Click to expand...

As was stated above, cooltubes are terrible at spreading light as is, so naturally, if you move it closer it will lose even more coverage...but if you had a hood that spread light evenly and well, you would see better results with it closer to the plants.

GorrillaPanic SNP said:

If you have your space properly laid out with the proper amount of lights and good hoods, the loss of light spread by lowering the light a few inches should be minimal if anything.,,plus by lowering the light you get greater intensity to the plants, more penetration through the canopy and other foliage, therefore boosting the size and quality of your harvest, especially on lower branches. So the pros out-weigh the cons. The lumen output by HID bulbs decreases exponentially as you increase distance. And it is impossible to "over saturate" a plant with light, the plant will use however much light you throw at it and the more the better.

Click to expand...

I have to wonder how you can claim the above with so much confidence? Having personalty done the legwork - using every logical permutation available - for over 10+ years and having the documented yields to show for it, it's safe to say that my experience differs greatly.

I wasn't asking how an air-cooled hood works, i was asking how well the glass panel keeps heat from penetrating.

Click to expand...

It doesn't. Why is that not brutally obvious?

And I agree, cooltubes do not spread light well. Sorry for the lack of info but I am not trying to improve upon a setup, I am just doing some "peer to peer" research on light spacing due to heat transfer and how well different hood's glass panels keep heat from radiating through.

Click to expand...

Ummm...good luck.

Simon

herbbilly said:

I see your point Simon in a large grow but I believe in small applications with proper ventilation you see a gain. I go 3'/2', 400 ,-6", no cool tube. I changed a lot at the same time manipulation, temp perfected, and saw a huge difference keeping complete canopy within 12"-18" of bulb.

Click to expand...

I don't think I was clear. Of course one can grow well without aircooled hoods.

The question then becomes, as you're venting the space, anyway, why not kill two birds with one stone? If you run your fan through an air-cooled reflector - I could suggest one with more detail - and then vent as usual, you're cooling the light at the same time. Win-win. Then, you can increase the light intensity and yield more bud. Again, win-win.

Simon

SimonD said:

I have to wonder how you can claim the above with so much confidence? Having personalty done the legwork - using every logical permutation available - for over 10+ years and having the documented yields to show for it, it's safe to say that my experience differs greatly.

Click to expand...

Do you think lower yields in association with closer lights could be related to heat-stress, burning, or any other heat related issues...or purely a light spread issue?

SimonD said:

It doesn't. Why is that not brutally obvious?

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It is brutally obvious. I'm basically asking a loaded question, which i know the answer to, but asking it none the less to make sure someone doesnt pop up and say "so and so hood brand blocks heat better"...

Lets say you had a glass panel that kept most, if not ALL, of the heat radiated from the bulb from passing through to the plants while still allowing the full spectrum of the bulb to reach the plants...do you think you could improve quality and yields by moving the light a few inches closer that normal?