Led Lighting: Sh:t Or Shinola?

[DemonTrich]

Light burn would be white

Nute burn is what your seedlings are showing. And for 2 weeks, those look ok for growth. Patients. You have 4-6 weeks before flip, then another 2 months to harvest. 7 days to dry, 3 weeks to cure if you desire to.

May want to grab a case of snickers. Perpetual is where it's at! But constant work.

 

[Uckemfup]

Yeah, I don't really know if that is light burn but looks more like nutrient burn. However with COBs spaced that close together why the hell would they use lenses, you just get a bunch of hot spots of intensity. I just posted a low cost entry level veg system that you can build for less than $200 and maybe even as low as $78. They are based on quantum QB120 boards. Have a look. I have seedlings and teenagers under it and I can get real close to the plants and they never burn. With my COB's and no lenses or reflectors I can get flowering plants a few inches away and no bleaching just real fast development. They seem to like being close to the light and the intensity is still less than it is on a sunny day at noon so they seem to be able to take all I can give them.

Link to my thred on QB120's: https://www.thcfarmer.com/community/threads/inexpensive-led-entry-point-qb120.95337/

Below is my veg tent. Lights are not real close here because I want a little more spread of the light right now but have run them as close as 3-4". In the flower room I run the COBs real close when the plants are asking for more light. These cost me $38 each to build and they put out 60 watts true power which is equivalent to about 80 watts HID!
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I’d love to use QBs for my next seedling/veg stage and save this light for my flower...ima take a look at ur setup homie, thanks!

 

[Uckemfup]

Light burn would be white

Nute burn is what your seedlings are showing. And for 2 weeks, those look ok for growth. Patients. You have 4-6 weeks before flip, then another 2 months to harvest. 7 days to dry, 3 weeks to cure if you desire to.

May want to grab a case of snickers. Perpetual is where it's at! But constant work.

I like work lol

 

[DGP]

I’d love to use QBs for my next seedling/veg stage and save this light for my flower...ima take a look at ur setup homie, thanks!

Low cost LED entry
https://www.thcfarmer.com/community/threads/inexpensive-led-entry-point-qb120.95337/

 

[Monster762]

Thank you yes it does answer alot and I see how the extra diffusion might weeken the intensity and thats what im after right now I believe I lack penetration and intensity may I ask whT cobs you use??? And like what sorta ave per watt return are you getting. Seems the more i read the less I know. I reAlly would love just some unbiased experiential advice

Led will lack penetration. Really I’ve come to penetration meaning about nothing. Cause I don’t care if you got 20000w of hid after 2 or 3 sets of leaves get in way there is no light getting in.

It’s all about training maximizing the light you have across an even canopy of bud sites. At end hid led cfl lec all the lower stuff is not top shelf. Only the upper plant where light is wide open to plant with no restriction. So real goal is exposing everything to that kind of light. Even with penetration after penetrating what’s left is so weak it’s almost useless. Any more penetration and your plant rolls up n smokes itself.
Canopy control. I’m learning it too.

 

[DGP]

How does the plant know how a photon was produced? A photon is a photon, it has a frequency and an intensity. From a physics standpoint how does a photon from one light source have more or less penetration than another?

Does a single HID bulb have more "penetration" than a bunch of LEDs spread over the grow canopy? Doesn't the diversity of angle (of the light beams) penetrate better when there are more of them spread out over an area? The geometry says it does. This idea of penetration is a myth propagated by people trying to sell lighting.

I would agree that plant training has a big impact because photons get blocked from the lower parts of the canopy whether the photon was produced bu HID, CFL, CMH, and arc of electricity, a tungsten filament or the sun or two stars colliding.

 

[DGP]

BTW, I am using LED COBs and the lower bud sites (not larf but lower ones that usually get blocked by the main colas and leaves) on my plants are developing so much better than in past 1k HPS grows. I believe it is because of the angle of the light coming from 12 places instead of basically one. The light coming from many points at many angles means the lower buds are getting more light. Not ideal light but better and a lot of these buds that would normally go in the trim pile for RSO or dry ice extraction are actually usable buds. This is what I mean by "diversity of angle".

Dee

 

[Wee Zard]

Wide array vs. point source.

Outside, the earth turns, the wind blows. and the angle changes all day.
Indoors, we use fans. My LEDs hang from a single chain, so they move when the fans kick in or turn off.

So much for "penetration". It's a non issue.
What is important is the inverse square law.

For a point source the intensity at 2" from the light is 1/4th what is is at 1". At 3 inches it is 1/9th!

This is not the case for an array, or fluorescent tubes.
The drop is less drastic for non-point source light.
And, of course the sun's intensity won't drop to 1/4th until it is another 93,000,000 miles away. :)

What this means is the farther your light is from the crown at full saturation, the more photon energy at the lower branches.
So, I can actually grow a 1 foot plant with onlty10 Watts of LED kept close to the crown. But to grow a 3 foot plant indoors, I use 56 Watts for 4 plants and put them outdoors to finish as 6 footers with buds all the way down.
The point is, penetration through the canopy is not an issue as long as winds blow, the earth turns, shadows shift and fans blow.
We can use arrays, and lenses to get around the ISL

Aloha,
Weeze

 

[DGP]

The inverse sq. law only applies in a true point source. COBs and LEDs aren't a true point source but a bunch of wide angle sources that all have Lambertian radiation patterns not single point source so it is had to figure out but a Lambertian pattern has a trig relationship that can be characterized. My point was that many sources make a diverse set of angles which improves the effectiveness of the fixture. If you get real close then yes you can use very low levels of power but as soon as the plants get bigger you will need the typical 50 watts per sq foot to get good coverage. Maybe we basically are agreeing but saying it a different way.

I believe the reason some plants like cannabis grow in a Christmas tree shape is to fully take advantage of the fact that the sun moves in a constantly changing angle. we train them to a more ideal shape for fixed light sources. I think this is why light movers are still used by some growers but I found them to be not so effective indoors and just another thing to fail.

I suppose the inverse square law is a good estimate for figuring out the relative light intensity at a given distance or change of distance.

Dee

 

[Homesteader]

From a physics standpoint how does a photon from one light source have more or less penetration than another?


Does a single HID bulb have more "penetration" than a bunch of LEDs spread over the grow canopy? Doesn't the diversity of angle (of the light beams) penetrate better when there are more of them spread out over an area? The geometry says it does. This idea of penetration is a myth propagated by people trying to sell lighting.

Blue light has more energy behind it and is able to penetrate deeper I assume which may be why some light sources do a better job at penetrating and some create more larf (haven't seen this myself though). I know this is water so it is not apples to oranges but I think it could be relevant.

 

[DGP]

Yes, Blue has more energetic photons but also takes more energy to make. Like I said every photon has frequency and intensity, the blue(er) it is then there is slightly more energy. I believe this is why MH for a given amount of energy input produces slightly less light intensity than HPS.

Dee

 

[Uckemfup]

BTW, I am using LED COBs and the lower bud sites (not larf but lower ones that usually get blocked by the main colas and leaves) on my plants are developing so much better than in past 1k HPS grows. I believe it is because of the angle of the light coming from 12 places instead of basically one. The light coming from many points at many angles means the lower buds are getting more light. Not ideal light but better and a lot of these buds that would normally go in the trim pile for RSO or dry ice extraction are actually usable buds. This is what I mean by "diversity of angle".

Dee

Truuuu. Even at early veg my lower sites are killing it w/COBs.