-
ICMag with help from Landrace Warden and The Vault is running a NEW contest in November! You can check it here. Prizes are seeds & forum premium access. Come join in!
25% more yield with a diffused LED ?
- Thread starter Kimes
- Start date
Ca++
Well-known member
I'm not sure anyone has had a plant burn with LED. Except where there has been (or almost been) physical contact.
Too much light leads to something more like a deficiency. We may see it start with the canopy being a lighter colour green. Later we might see albino traits. This is typically the outcome of high red.
As we increase the light, plants grow more. As we keep increasing the light, a time comes when it starts doing damage. The plant will now use resources for repairs. All we will see is the plant slow down. Further increases lead to greater levels of shut down. Studies looking at plants surviving the mid-day sun catalogue these mechanisms. At some point, we turn up the light beyond what the repair processes can manage. Here we start to see lighter tops and interveinal chlorosis, that has most growers looking at their feed as a way to make the plants look better. Which is often a mistake.
That was all about red damage, as it's the better catalogued scenario. Different colours have different effects. Changes within the plant, that work together to grow it. For a moment, look at building a wall. We use sand, cement and water as the main elements for our mortar. They must be proportionate. Too much of any one, and the mix doesn't work.
Back to the plants, it's the same. They evolved under sunlight with equal amounts of Blue Green and Red. They can tolerate some change in ratio's but it requires effort. Repair effort. So using unbalanced light promotes the plants shutdown at lower light levels.
This is so pronounced, that tests done with a good white balance, found there was no upper limit to the light you can use. They went as far as 2500ppfd. All our plants are different, but by using 40% red (20 blue 20 green, I was left to guess) the maximum light before issue was 700-800ppfd (I forget exactly)
So in short, a good mix of rgb poses very little risk of light damage. However, testing shows that more than 40% red or blue is damaging. Causing the plants to do work, they might not even be able to do. Depending on just how hard you are pushing them.
All this is presuming you want to push for the maximum. If you are happy with 500ppfd then you actually want quite a bit of red. It's economically viable. At just 500ppfd the plants not struggling, and will find the extra red easier to tolerate, than at higher ppfd. Red light is efficient to make, and if lighting is your main cost, then a 500ppfd grow using the most efficient lighting, may be the most profitable method. Strain dependent.
Cerathule
Well-known member
Ca++, I'm placing you now on ignore and would like you don't respond to my posts anymore.
What you are doing right now is trolling and gaslighting. You have objected to each and every posts I've made so far but in all cases, completely missed the points I raised.
In some examples you brought absurdities like the Big Bang or gravitational lensing forth to defend your position that even lasers obey the inversed-squared law. When, for practical purposes, galactic dimensions don't matter.
Plus, you cannot even read a simply formula or realize a radius is a distance as well.
And right now you are objecting to something that is so easy to understand and you are essentially turning my written words around.
I've exlained it in 2 previous posts already... And it has nothing to do with the internal calculation to convert the number to a lux/ppfd (m^2) metric.
Neither with angle of incident correction.
The leaf will get more light as these sensors register, it neglects ambient stray light coming from directions outside its viewing angle.
Have a nice sunday
Ca++
Well-known member
It's all good. I couldn't be bothered with it either. Lets compress what happened though. Lots of cut&paste. Lost track of what he had said. Tried to turn it around. Was shown what he said, and chucked his dummy out the pram. Giving reasons it's my fault that he doesn't want to cross paths again.
I did say I didn't want to talk about depreciation with him, and have not done so since. Is that trolling? Perhaps him still going on about it is trolling? Who is talking about it.
This is what we both want. I don't think anyone need concern themselves with it.
Obviously, if someone starts on about how their light meter works, and is incorrect, I'm going to clear that up. For everybody. That is the whole point of a discussion forum. It could of been anybody saying it.
Looks like the sunshine is back..
Last edited:
Cerathule
Well-known member
Think I found an approach but this is based on geometrical models and thus idealistic:
Formula:
1÷(sin(<B÷4)^2)
<B= Beam angle of the diode
Results:
360° = 1
180° = 2
140° = ~3.04
120° = 4
90° = ~6.83
60° = ~14.93
So a 60° light dispersion angle will have a x14.93 higher intensity than a spherical light emitter - at the same distance measured when releasing the same amount of photons per second.
120° beam angles are most of the industries standards. Still 4 times higher than a free-hanging HID.
Both the beam-angle and how many photons are generated by a fixture can be gathered from its datasheet.
But a fixture or diode doesn't release all the light isotropically and there are other losses as well. But just to get an idea how reflectors, lenses etc can adjust the beam angle and impact on the density of photons (on paper).
Yeah, that's the basis. It tells you the ratio of the illuminated area versus the area of the whole sphere.
Trouble is when you have multiple leds in a fixture, something like a QB, then the math/geometry gets way harder.
Other factors need to be included, related to efficiency at different temps for example.
Cheers
Trouble is when you have multiple leds in a fixture, something like a QB, then the math/geometry gets way harder.
Other factors need to be included, related to efficiency at different temps for example.
Cheers
I can assure you my Cree cobs feel quite warm when i put my hand under them, warm enough to dehydrate and stress a plant if it's too close.
Cerathule
Well-known member
Still, no IR emission in these SPDs. A boatload of visible light that is. And some convective heat yes
Ca++
Well-known member
Light heats surfaces, just as a microwave oven heats things without being in the IR range.
The IR output of LED lights is generally a function of how hot they run. Some have dedicated IR emitters, but a white cob is a white cob. It's IR output is about how hot it runs. They do run quite hot. If we could run them cooler, we would drive them harder to make them hot again. There output being mostly capped by thermal issues.
LEDs don't make their light by being hot. Not in the way most lighting does, which is getting so hot they glow. For most lighting, heat comes before light. Even for LED, there is more heat created than light. It's just not the primary reason for there being light.
As a hot body, warming IR is present. Importantly though, it's about the coldest light source you can get. It's not likely to be causing problems related to excess heat.
What COB is it? Perhaps it's red content was ~620 when new, and has shifted towards the orange with age. They do.
This might leave the blue making up a relatively high portion of the spectrum emitted. I don't know much of the excess blue effects, but don't think it's excess red.
One stand out difference with the goatcheese grow, is the very low RH. In the 20s. So this drying out being blamed on the lighting, might itself need more consideration. The goat grow behaves better at higher RH, but higher is 30%. Unless there has been some changes I missed.
If we increase leaf temp with more heat radiation, at a gradual rate, rather than switching on a superbowl lighting rig, changes should be easier to pick out.
Plants have evolved to compensate, within a certain range of expectations. Modulating their water loss, by changing the size of the shared pores that regulate moisture loss and CO2 intake. Physically speaking, these pores are like mouths with puffy lips, called guard cells. When the lips are blown up with water, their mouths are open. We get a lot of water and air movement. If the air is too dry or the heat to high, these lips are there to loose moisture from themselves, closing the mouth. It's an equilibrium, where moisture loss of the guard cells, regulates water loss of the pores (stomata).
I think in the goat grow, we have pretty small stomata due to the water losses of having 20% RH.
This means less co2 for the plant, which is a cap on growth rate.
More light increases photosynthesis. A process that leads to water loss. This extra light normally carries some heat energy that would further close the pores. The LED does little.
This is a more a list of circumstances than any sort of fact list regarding a specific grow. However, we can see that low RH throttles growth rates through co2 regulation. Then higher light demands more co2. While increasing water loss, that isn't countered to the usual degree by leaf warming efforts.
A sudden collapse within an hour of lighting up the stadium, seems to be exhaustion. Many people hit a similar wall, though at different speeds, with raised RH and room temps the key.
I don't see how diffusing the light will help under the circumstances. Though it may lead to more even light over the plant, rather than so concentrated on the tops.
The IR output of LED lights is generally a function of how hot they run. Some have dedicated IR emitters, but a white cob is a white cob. It's IR output is about how hot it runs. They do run quite hot. If we could run them cooler, we would drive them harder to make them hot again. There output being mostly capped by thermal issues.
LEDs don't make their light by being hot. Not in the way most lighting does, which is getting so hot they glow. For most lighting, heat comes before light. Even for LED, there is more heat created than light. It's just not the primary reason for there being light.
As a hot body, warming IR is present. Importantly though, it's about the coldest light source you can get. It's not likely to be causing problems related to excess heat.
What COB is it? Perhaps it's red content was ~620 when new, and has shifted towards the orange with age. They do.
This might leave the blue making up a relatively high portion of the spectrum emitted. I don't know much of the excess blue effects, but don't think it's excess red.
One stand out difference with the goatcheese grow, is the very low RH. In the 20s. So this drying out being blamed on the lighting, might itself need more consideration. The goat grow behaves better at higher RH, but higher is 30%. Unless there has been some changes I missed.
If we increase leaf temp with more heat radiation, at a gradual rate, rather than switching on a superbowl lighting rig, changes should be easier to pick out.
Plants have evolved to compensate, within a certain range of expectations. Modulating their water loss, by changing the size of the shared pores that regulate moisture loss and CO2 intake. Physically speaking, these pores are like mouths with puffy lips, called guard cells. When the lips are blown up with water, their mouths are open. We get a lot of water and air movement. If the air is too dry or the heat to high, these lips are there to loose moisture from themselves, closing the mouth. It's an equilibrium, where moisture loss of the guard cells, regulates water loss of the pores (stomata).
I think in the goat grow, we have pretty small stomata due to the water losses of having 20% RH.
This means less co2 for the plant, which is a cap on growth rate.
More light increases photosynthesis. A process that leads to water loss. This extra light normally carries some heat energy that would further close the pores. The LED does little.
This is a more a list of circumstances than any sort of fact list regarding a specific grow. However, we can see that low RH throttles growth rates through co2 regulation. Then higher light demands more co2. While increasing water loss, that isn't countered to the usual degree by leaf warming efforts.
A sudden collapse within an hour of lighting up the stadium, seems to be exhaustion. Many people hit a similar wall, though at different speeds, with raised RH and room temps the key.
I don't see how diffusing the light will help under the circumstances. Though it may lead to more even light over the plant, rather than so concentrated on the tops.
Last edited:
Kimes
Well-known member
Probably not. Not with these strains at least. Later I might for the giggles, with clones.. Let´s see.
Diffusers definitely work!
I got the diffuser strips installed on my small veg/bloom light yesterday and the improvement is very clear. I can now keep the light much closer to the plants without seeing stress symptoms- without the tops dehydrating.
According to the shop where i got these strips the light transmittance is 93%= you will lose 7% of the light
..but i can now keep the light atleast 20% closer to the plants and it’s quite clear the plants/tops are getting more light now.
I don’t have a light meter or an app on my phone but the difference is so noticeable that i don’t need a meter to give me the exact numbers.
I think the biggest factor in this is that the diffuser strips act as a heat shield. The beams are still there but the diffusers (mine look like clear plastic but can handle temperatures up to 100 C) take out a good bit of the heat radiation off these photon beams.
I got the diffuser strips installed on my small veg/bloom light yesterday and the improvement is very clear. I can now keep the light much closer to the plants without seeing stress symptoms- without the tops dehydrating.
According to the shop where i got these strips the light transmittance is 93%= you will lose 7% of the light
..but i can now keep the light atleast 20% closer to the plants and it’s quite clear the plants/tops are getting more light now.
I don’t have a light meter or an app on my phone but the difference is so noticeable that i don’t need a meter to give me the exact numbers.
I think the biggest factor in this is that the diffuser strips act as a heat shield. The beams are still there but the diffusers (mine look like clear plastic but can handle temperatures up to 100 C) take out a good bit of the heat radiation off these photon beams.
Ca++..
Do you mean the diffuser material i have? Yea, it looks just like clear plastic – no texture on it what so ever; The leds look more or less the same thru the plastic as before, but i think the plastic sheets act as a heat shield absorbing some of the heat radiation of the photon beams
It’s just plain cover plastic used in home lighting. It’s quite thin, under 1 mm thick but still ridged enough. It cost me 5-6 euros per 2 meter strip, so it was a cheap solution for me.
..and maybe it will pay itself back to me in time if i don’t have to use as much CalMag as before. LOL
The photo of the veg-light is abit dark but i’m in a hurry and don’t have the time to find the proper camera setting – But you get the idea.
Do you mean the diffuser material i have? Yea, it looks just like clear plastic – no texture on it what so ever; The leds look more or less the same thru the plastic as before, but i think the plastic sheets act as a heat shield absorbing some of the heat radiation of the photon beams
It’s just plain cover plastic used in home lighting. It’s quite thin, under 1 mm thick but still ridged enough. It cost me 5-6 euros per 2 meter strip, so it was a cheap solution for me.
..and maybe it will pay itself back to me in time if i don’t have to use as much CalMag as before. LOL
The photo of the veg-light is abit dark but i’m in a hurry and don’t have the time to find the proper camera setting – But you get the idea.
If cost was the only problem, maybe finding cheaper cal mag sources would be better. Yet, we don't know, till we get some responses on how much Ca is "needed" and if we need more or less of it to be good for smoking qualities of the end product. I can certainly see the plants are happier when well feed, even if closer to the lights. But I couldn't tell you more than that. We need a side by side by a reputable grower or even some real science on this.
Riiiiight...
So if the tops get less light this means also the lower growth gets less light.
The net photons are reduced by 7%, so why not just raise the light by 10% of distance from tops?
I have serious doubts about how this issue gets pictured here...
Cheers
So if the tops get less light this means also the lower growth gets less light.
The net photons are reduced by 7%, so why not just raise the light by 10% of distance from tops?
I have serious doubts about how this issue gets pictured here...
Cheers
