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A beginners guide to LED's

High-Dro Mephisto

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Thought I’d share this video .... Long video and it starts kinda slow but very educational .... Highly recommend for anyone considering a new purchase or anyone wanting to get smarter ..... he tests some 27 lights, is yours on the list, mine is and it sits at number two ..... BUT not all manufacturers are represented.

Well I can see these guys came really close to my same results. Part of the reason I reccomended the HLG and Fluence lights on the guide. Very good and effecient LED's. There are a few on here though I want to check out now and even some I had glanced at and thought they wouldnt be bad but performed very poorly it seems.
 

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:rofl:
Well I can see these guys came really close to my same results. Part of the reason I reccomended the HLG and Fluence lights on the guide. Very good and effecient LED's. There are a few on here though I want to check out now and even some I had glanced at and thought they wouldnt be bad but performed very poorly it seems.
Ya you see the numbers on some of the popular lights, names without to protect innocent, running around AFN and other boards and yet see their results and it now confirms our suspicions the plant is a WEED ............... :rofl:
 

L0wbob2017

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Please dont take any of this offensive!

First of all, plants use light for waaay more than just photosynthesis, therefore a varying white (full) spectrum is a must for optimal results.

Wavelengths:



Light is a photon that acts like a wave. Imagine a sinus wave like this. The faster this happens the higher its frequency is.
A high frequency results in a shorter wavelength ( for example ~460nm - blue ). The lower the frequency the longer the wavelength ( for example ~640nm - red )



---

Humans can see light in a range of about 380 - 780nm. Also the human eye can see some colors better than others and this also depends on the day or night cycle.
(Theoretically you can name this the human "action spectrum" )



The big one ( K' ) is called scotopic and describes the average spectral sensitivity of human visual perception of brightness at night ( at night you are more sensitive for blue - maybe some of you know the bluefilter of your smartphone, thats why it even exists )
The small one ( K ) is called photopic and describes the same for daytime ( you are more sensitive to green )

Every spectrum ( this should better be called "spectral power distribution" ) you can see in a datasheet is normalized for this curve, so you know what a human eye would see at the day because it was invented for artificial working lights.
This results in the fact, that a spectrum in a LED-datasheet is not what plants see.

---

Back in the time it was thought that plants only use light within the range of 400 - 700nm. Therefore they invented the so called PAR-spectrum. ( photosynthetic active radiation )



PAR itself does not have any unit and is only a curve that sets the efficiency on 1 for a range of 400 - 700nm. This also means that every photon is equal in terms of photosynthesis ( which is not the case ).
To measure this radiation the so called photosynthetic photon flux ( PPF ) is used and it has the unit µmol/s.

If you have a PAR-value for a specific lightsource this just tells you the sum of all photons within the range of 400 - 700nm that get emitted in 1 second.

In the last 2 years a new measurement is coming in some horticulture datasheets. It is called photobiological active radiation ( PBAR ). It is basically the same as PAR but with a range from 200 - 800nm.
Because the PPF-value of a lightsource does not say much about what will hit the plants at a certain distance and McCree found out that photosynthesis is a quantum process which depends more on the amount of incoming photons than on the wavelength ( color ), the photosynthetic photon flux density ( PPFD ) was created. It is a measurement of how many photons hit one squaremeter. Its unit is µmol/(m²*s).

About the range you should aim for it is about 400 - 600 µmol/(m²*s) if you dont live in a very industrial part of your city where the ambient CO2 levels are higher. For effective usage of more light you should be about 600ppm CO2.

---

To be able to compare photons of different wavelengths these have to be equalized in terms of energy. Like aforementioned "blue" light does have more energy than "red" light.
Therefore you take 1 Joule of energy and calculate how many photons of a certain wavelength you can produce with it. The results get normalized by the wavelength with the lowest energy which is 700nm.


You can see that the energy of a photon with a wavelength of 700nm would be close to 60% of the energy of a photon with a wavelength of 400nm. This curve is also called the "PAR spectral response".

---




Since PAR, PBAR, PPF or PPFD all assume that every photon is equal in terms of photosynthesis ( which it isnt ) the so called Yield photon flux ( YPF ) was invented. It has the range from 360 - 760nm.
This takes the photosynthetic reaction of the plant depending on the energy of the incoming photon ( normalized with the PAR spectral response ).
You also can call this the action spectrum.

Over the time there were created some standards/DINs/ISOs ( whatever you wanna call them ). [ McCree, Inada, Tazawa, DIN 5031-10, Dodillet ]
McCree and Inada made the start with a massive data-collection which has been used years later by Tazawa to make some nice graphs





---

To make the difference between PPF and YPF a bit more clearer

(McCree-version)

(DIN-Version from 2018)


---

So after all that you can now take the famous average action spectrum and try to adopt it to one specific planttype that changes its action spectrum depending on age and veg/bloom stage. ( hint )
But first you have to take a spectrum of a LED, renormalize it with the action spectrum of humans at daylight and normalize it back with the action spectrum for plants.
Then you know how the average tested plants would see your light. With this you also could calculate how effective it would be compared to a theoretically perfect spectrum.

To see the difference between the datasheet and what plants see i made a post a few months ago. Here is the graphic from that post:



The dashed lines are from the datasheet and the not-dashed lines are what the plant would actually see.

---

Coming to that hint i made before.
If someone claims he has a light that is optimized for a specific planttype and it has only 3 possible spectra ( veg, bloom, veg + bloom ) it most likely is not optimized.
Since the incoming light spectrum varies within the day and the year it basically would need a lot of different spectra with the right intensities.



For a "perfect spectrum" this also means it cant be only one white ( full ) spectrum from seed to harvest.
In addition to this:

The temperature of a white ( full spectrum ) light source has something to do with the so called "black body radiation". All normal matter that has a temperature of above "absolute zero" will emit electromagnetic radiation which represents the conversion of a body's internal energy into electromagnetic energy, the so called thermal radiation. You emit these by urself and can sense warmer body's ( for example a stove )

Now imagine an opaque and non-reflective body. Thats a so called "black body". If you heat this up to a certain temperature, it will also emit an electromagnetic radiation. This radiation is at first only in the for humans invisible infrared spectrum. The more you heat it up, the higher its frequency gets. If you remember from the first explanation, the higher the frequency, the "bluer" it gets.

It is very important that the temperature is measured in kelvin, which has its start at the absolute zero with a 0.
This results in 0°C = 273.15K or 32°F = 273.15K

Now if you heat that black body more and more it will emit a see-able spectrum starting in the dark reddish and ending in something very blueish/violette till the human eye cant see it and it gets UVA.
Here is a picture for imagination


Numbers are the temperature in kelvin.




So now this is given, it is possible to calculate the black-body temperature of our sun. The radiation from our sun hits our atmosphere and gets filtered that way. Depending on the thickness and mixture of the air ( depends on the time of the day and your location on earth and its actual season ) between the earths surface and the suns radiation, this gets more or less filtered resulting in different "ground reaching" spectra.

This results in about this:


The yellow curve in the background would be the ideal black body with a temperature of 5900K
The orange one is what hits the earths atmosphere
The rainbow colored one is what hit the ground when the sun reaches 90 degrees ( when it is directly over you and has the minimal amount of air-mass between )

---

The data is interesting and yes, there is no perfect spectrum. Yet white LEDs are showing superior growth compared to 5x more expensive " horticultural" LEDs. Makes you wonder why they are still mostly Red/Blue combinations with a little IR and UV tossed in. When people are pulling yeilds of high quality buds exceeding 2.0 gpw ( yeah yeah, not the best metric but it makes a point ) according to anecdotal evidence, something is obviously on point. Supplemental Deep red and UV may or may not be of value, I've not seen definitive evidence that it does. if you have information to support its worth, that would be a worthy post also. Personally, i'd put my DIY QB based light up against any horticultrual LED based light including Fluence for results. I'm sure though, that based on the science you present, better LEDs for horticulture will be available one day. In the meantime, you can't complain about the results of White LEDs!
There is some evidence that UV-B, UV-A, blue, red and far-red photons are used by plants for further development. The only thing is that the results of using them dont show their big part in the "photosynthesis"- sector. They still contribute to photosynthesis.

To explain this i will quote my starting sentence:
First of all, plants use light for waaay more than just photosynthesis, therefore a varying white (full) spectrum is a must for optimal results.
With varying i meant supplemantal UV-B, UV-A, blue, red and far-red in varying intensites over the day of your plants ( 18 or 12 hours ).

Plants use light for other processes, in this case the so called "tropism". Here are the different types:

-Aerotropism, growth of plants towards or away from a source of oxygen
-Chemotropism, movement or growth in response to chemicals
-Electrotropism, movement or growth in response to an electric field
-Exotropism, continuation of growth "outward," i.e. in the previously established direction
-Geotropism (or gravitropism), movement or growth in response to gravity
--Apogeotropism, negative geotropism
-Heliotropism, diurnal motion or seasonal motion of plant parts in response to the direction of the sun, (e.g. the sunflower)
--Apheliotropism, negative heliotropism
-Hydrotropism, movement or growth in response to water; in plants, the root cap senses differences in water moisture in the soil, and signals cellular changes that causes the root to curve towards the area of higher moisture
--Prohydrotropism, positive hydrotropism
-Hygrotropism, movement or growth in response to moisture or humidity
-Magnetotropism, movement or growth in response to magnetic fields
-Orthotropism, movement or growth in the same line of action as the stimulus
-Plagiotropism, movement or growth at an angle to a line of stimulus such as gravity or light
-Phototropism, movement or growth in response to lights or colors of light
--Aphototropism, negative phototropism
--Skototropism, negative phototropism of vines
-Thermotropism, movement or growth in response to temperature
-Thigmotropism, movement or growth in response to touch or contact

The important one for this explanation is the Phototropism.

Photomorphogenesis is a light depending effect , where plant growth patterns respond to the light spectrum. It is very important to understand that this is a completely separate process from photosynthesis where light is more like an energy-source.

Phytochromes, cryptochromes and phototropins are photochromic receptors that restrict the effect of light to the UV-B, UV-A, blue, red and far-red parts of the electromagnetic spectrum ( light-source ). There are at least three stages of plant development where photomorphogenesis occurs: seed germination, seedling development, and the switch from the veg to bloom ( so called photoperiodism).

Phytochromes have action maxima in red and far-red, cryptochromes have several action maxima in different "blue"-wavelengths and UV-A, and the so called UVR8 receptors are for the harmfull UV-B.








There is a list from Tazawa about some effects:


---

So if you have supplemental wavelengths of the aforementioned ones that are not for photosynthesis but for photomorphogenesis you should see way better results than just with a full white spectrum ( even if you have the same radiation-power ).

---

This had me pretty much before i skipped my hobby topic to mushrooms :D


Please keep in mind that the following was a personal decision!

The last thing i wrote in my notes was:

Idea for the improved Light-concept that uses artificial light for plants that perform photoperiodism:
UV-B Supplement, 10 minutes per day the last 3 weeks of bloom ( no LED-source. My example would have used the AgroMax Pure UV )
UV-A Supplement, dimmable for all stages except germination
even mix with 5700K and 3000K individual channels each dimmable. 5700K is 100% for veg, 50% for bloom. 3000K is 50% for veg, 100% for bloom. Both dimmable and evenly distributed. For all stages except germination
Red Supplement, 630nm & 660nm, dimmable, only for germination and bloom, in bloom Red-Supplement for 15 minutes before the rest kicks in. ( so 15 minutes longer than the rest except IR )
Far-Red Supplement, only for bloom and only the last hour of the day ( + 15 minutes after the rest goes out )

I never had the chance to try it, but maybe some time i will. Till then maybe someone else gives this a try.
 
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High-Dro Mephisto

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In addition to this:

The temperature of a white ( full spectrum ) light source has something to do with the so called "black body radiation". All normal matter that has a temperature of above "absolute zero" will emit electromagnetic radiation which represents the conversion of a body's internal energy into electromagnetic energy, the so called thermal radiation. You emit these by urself and can sense warmer body's ( for example a stove )

Now imagine an opaque and non-reflective body. Thats a so called "black body". If you heat this up to a certain temperature, it will also emit an electromagnetic radiation. This radiation is at first only in the for humans invisible infrared spectrum. The more you heat it up, the higher its frequency gets. If you remember from the first explanation, the higher the frequency, the "bluer" it gets.

It is very important that the temperature is measured in kelvin, which has its start at the absolute zero with a 0.
This results in 0°C = 273.15K or 32°F = 273.15K

Now if you heat that black body more and more it will emit a see-able spectrum starting in the dark reddish and ending in something very blueish/violette till the human eye cant see it and it gets UVA.
Here is a picture for imagination


Numbers are the temperature in kelvin.




So now this is given, it is possible to calculate the black-body temperature of our sun. The radiation from our sun hits our atmosphere and gets filtered that way. Depending on the thickness and mixture of the air ( depends on the time of the day and your location on earth and its actual season ) between the earths surface and the suns radiation, this gets more or less filtered resulting in different "ground reaching" spectra.

This results in about this:


The yellow curve in the background would be the ideal black body with a temperature of 5900K
The orange one is what hits the earths atmosphere
The rainbow colored one is what hit the ground when the sun reaches 90 degrees ( when it is directly over you and has the minimal amount of air-mass between )

---



There is some evidence that UV-B, UV-A, blue, red and far-red photons are used by plants for further development. The only thing is that the results of using them dont show their big part in the "photosynthesis"- sector. They still contribute to photosynthesis.

To explain this i will quote my starting sentence:

With varying i meant supplemantal UV-B, UV-A, blue, red and far-red in varying intensites over the day of your plants ( 18 or 12 hours ).

Plants use light for other processes, in this case the so called "tropism". Here are the different types:

-Aerotropism, growth of plants towards or away from a source of oxygen
-Chemotropism, movement or growth in response to chemicals
-Electrotropism, movement or growth in response to an electric field
-Exotropism, continuation of growth "outward," i.e. in the previously established direction
-Geotropism (or gravitropism), movement or growth in response to gravity
--Apogeotropism, negative geotropism
-Heliotropism, diurnal motion or seasonal motion of plant parts in response to the direction of the sun, (e.g. the sunflower)
--Apheliotropism, negative heliotropism
-Hydrotropism, movement or growth in response to water; in plants, the root cap senses differences in water moisture in the soil, and signals cellular changes that causes the root to curve towards the area of higher moisture
--Prohydrotropism, positive hydrotropism
-Hygrotropism, movement or growth in response to moisture or humidity
-Magnetotropism, movement or growth in response to magnetic fields
-Orthotropism, movement or growth in the same line of action as the stimulus
-Plagiotropism, movement or growth at an angle to a line of stimulus such as gravity or light
-Phototropism, movement or growth in response to lights or colors of light
--Aphototropism, negative phototropism
--Skototropism, negative phototropism of vines
-Thermotropism, movement or growth in response to temperature
-Thigmotropism, movement or growth in response to touch or contact

The important one for this explanation is the Phototropism.

Photomorphogenesis is a light depending effect , where plant growth patterns respond to the light spectrum. It is very important to understand that this is a completely separate process from photosynthesis where light is more like an energy-source.

Phytochromes, cryptochromes and phototropins are photochromic receptors that restrict the effect of light to the UV-B, UV-A, blue, red and far-red parts of the electromagnetic spectrum ( light-source ). There are at least three stages of plant development where photomorphogenesis occurs: seed germination, seedling development, and the switch from the veg to bloom ( so called photoperiodism).

Phytochromes have action maxima in red and far-red, cryptochromes have several action maxima in different "blue"-wavelengths and UV-A, and the so called UVR8 receptors are for the harmfull UV-B.








There is a list from Tazawa about some effects:


---

So if you have supplemental wavelengths of the aforementioned ones that are not for photosynthesis but for photomorphogenesis you should see way better results than just with a full white spectrum ( even if you have the same radiation-power ).

---

This had me pretty much before i skipped my hobby topic to mushrooms :D


Please keep in mind that the following was a personal decision!

The last thing i wrote in my notes was:

Idea for the improved Light-concept that uses artificial light for plants that perform photoperiodism:
UV-B Supplement, 10 minutes per day the last 3 weeks of bloom ( no LED-source. My example would have used the AgroMax Pure UV )
UV-A Supplement, dimmable for all stages except germination
even mix with 5700K and 3000K individual channels each dimmable. 5700K is 100% for veg, 50% for bloom. 3000K is 50% for veg, 100% for bloom. Both dimmable and evenly distributed. For all stages except germination
Red Supplement, 630nm & 660nm, dimmable, only for germination and bloom, in bloom Red-Supplement for 15 minutes before the rest kicks in. ( so 15 minutes longer than the rest except IR )
Far-Red Supplement, only for bloom and only the last hour of the day ( + 15 minutes after the rest goes out )

I never had the chance to try it, but maybe some time i will. Till then maybe someone else gives this a try.
Ha ha. You have too much time on your hands lol. You either took some serious courses on light and botany, work in this industry, or both. Networking is the only subject I could that in depth into if I wanted. I want to still expand on the base guide but I would never be able to go in to details like these without some serious studying for sure. I am very good at capturing concepts quickly but details tend to slip my mind for sure. Thank you for sharing
 

L0wbob2017

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Ha ha. You have too much time on your hands lol. You either took some serious courses on light and botany, work in this industry, or both. Networking is the only subject I could that in depth into if I wanted. I want to still expand on the base guide but I would never be able to go in to details like these without some serious studying for sure. I am very good at capturing concepts quickly but details tend to slip my mind for sure. Thank you for sharing
Haha nope, i just learned it because of personal interest. You can learn all of this for free on the internet.
I am studying IT at the university. :crying:
 
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Only thing is... I have to build them if u don’t want to spend $700 fucking dollars :/

Worth it if you DIY tho :)


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Money is not issue .... In fact lights your lights are Killer and efficiency is off charts but for my 2x4 I’m more than happy with the Optic 4 ...... now later when I outfit a new 4x4 those lights will be under consideration.
 

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Has anybody used the Chil LED 226? It has red, blue, and white LEDs...as well as some UV diodes. Their website is giving me some kind of error right now. There is a YouTube video explaining all of the specs of this light that is pretty interesting.


Sent from my LGL84VL using Tapatalk
 

High-Dro Mephisto

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Has anybody used the Chil LED 226? It has red, blue, and white LEDs...as well as some UV diodes. Their website is giving me some kind of error right now. There is a YouTube video explaining all of the specs of this light that is pretty interesting.


Sent from my LGL84VL using Tapatalk
I took a few minutes out to look over there site earlier. Seems they dont have any current lights available. They seem to be focused on the science behind which is always good. I would be curious about a light that has UV Leds on it from the start. Narrow Band UV rays are good at low doses towards the end of the grow. supplementing them throughout might actually do more bad than good.
 

pop22

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Chill has a good rep and for anyone who has heard of Growmau5 from youtube, he now works for ChillLED

Has anybody used the Chil LED 226? It has red, blue, and white LEDs...as well as some UV diodes. Their website is giving me some kind of error right now. There is a YouTube video explaining all of the specs of this light that is pretty interesting.


Sent from my LGL84VL using Tapatalk
 

L0wbob2017

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@pop22

i hope that answers it a bit?!

There is some evidence that UV-B, UV-A, blue, red and far-red photons are used by plants for further development. The only thing is that the results of using them dont show their big part in the "photosynthesis"- sector. They still contribute to photosynthesis.

To explain this i will quote my starting sentence:

With varying i meant supplemantal UV-B, UV-A, blue, red and far-red in varying intensites over the day of your plants ( 18 or 12 hours ).

Plants use light for other processes, in this case the so called "tropism". Here are the different types:

-Aerotropism, growth of plants towards or away from a source of oxygen
-Chemotropism, movement or growth in response to chemicals
-Electrotropism, movement or growth in response to an electric field
-Exotropism, continuation of growth "outward," i.e. in the previously established direction
-Geotropism (or gravitropism), movement or growth in response to gravity
--Apogeotropism, negative geotropism
-Heliotropism, diurnal motion or seasonal motion of plant parts in response to the direction of the sun, (e.g. the sunflower)
--Apheliotropism, negative heliotropism
-Hydrotropism, movement or growth in response to water; in plants, the root cap senses differences in water moisture in the soil, and signals cellular changes that causes the root to curve towards the area of higher moisture
--Prohydrotropism, positive hydrotropism
-Hygrotropism, movement or growth in response to moisture or humidity
-Magnetotropism, movement or growth in response to magnetic fields
-Orthotropism, movement or growth in the same line of action as the stimulus
-Plagiotropism, movement or growth at an angle to a line of stimulus such as gravity or light
-Phototropism, movement or growth in response to lights or colors of light
--Aphototropism, negative phototropism
--Skototropism, negative phototropism of vines
-Thermotropism, movement or growth in response to temperature
-Thigmotropism, movement or growth in response to touch or contact

The important one for this explanation is the Phototropism.

Photomorphogenesis is a light depending effect , where plant growth patterns respond to the light spectrum. It is very important to understand that this is a completely separate process from photosynthesis where light is more like an energy-source.

Phytochromes, cryptochromes and phototropins are photochromic receptors that restrict the effect of light to the UV-B, UV-A, blue, red and far-red parts of the electromagnetic spectrum ( light-source ). There are at least three stages of plant development where photomorphogenesis occurs: seed germination, seedling development, and the switch from the veg to bloom ( so called photoperiodism).

Phytochromes have action maxima in red and far-red, cryptochromes have several action maxima in different "blue"-wavelengths and UV-A, and the so called UVR8 receptors are for the harmfull UV-B.








There is a list from Tazawa about some effects:


---

So if you have supplemental wavelengths of the aforementioned ones that are not for photosynthesis but for photomorphogenesis you should see way better results than just with a full white spectrum ( even if you have the same radiation-power ).
 
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