LED Lab 2009

[MrNebulized]

Now we are getting to the true experimenters. I see that this thread is getting interesting, arguing the value of certain light is a good question. Cannabis is a weed, it grows anywhere in the world under nearly any circumstances. It would not surprise me to find that there are certain strains that love UV lighting while others can't stand it, some may love far red and some just red.

It is a pretty interesting concept that we may all be on different pages anyways. If cannabis is different on every continent(and it is) I would assume that they evolved to their surroundings. My quest for the nearly perfect LED(as I think each strain will love things differently) isn't over but I would definitely like to continue. My car broke and now I can't get started on the LED like I had initially hoped.

 

[billyjojimbob11]

Yes, I agree, and I have been trying to find lit on the difference of spectrums at different parts of the earth and the absorbtion rates of plants in various parts of the world. Most studies I have seen show plants native to EU, china and the US. I haven't found studies of plants native to areas closer to the equator and the tropic of cancer which Cannabis usually is found and the absorbtion colors and rates those plants have vs the ones in the northern Hemisphere. Also worth looking into is the effect that maybe using 430-440nm dom blue has in Chloro B during flower. Basically, we have to be narrowing this down, whether it be one of the following or all of the below:

Wrong color Red
Not broad enough red spectrum (very possible)
Not using amber dominate (will know soon as I try amber and yellow 50% to red 40% WW 10%)
Not enough full spectrum (small possibility)
Not using enough phosphored colors (white) (white does play some minor role in plant mechanics and processing efficiency)
Not using enough uv or far blue (i doubt it seriously, but may improve oils and aroma's)
Not enough intensity (obviously more yield with more lux)
Not using more culminated light (I'm seeing improved results no with narrower culminating lenses)
Not penetrating well
Wrong red/blue/far blue/far red ratio (very possible)
Wrong color blue for flower (slim chance, but possible)
Not enough farred (possibly)
Too much farred (highly unlikely)
Not enough blue light @ flower (not likely)

I think that covers most of the possible problems we face, please add more if you think of possibilities.

I have been crossing these off or concluding their roles in the answer for the past year.

 

[knna]

billyjojimbob11, i think you forget the main one:

-Not enough light, of any PAR wavelenght.

I believe most LED grows that fail does it due to not using enough light.

I insist we need to consider the amount of light together with spectral quality. First, because we need to know the relative spectral efficacy of each color mix, and that is only possible comparing yield with amount of light used.

Consider the photosyntethic production as the result of multiplying the gross amount of PAR photons by the spectral efficacy of the color mix:

Y= E * θ (λ)

where

Y=yield

E=amount of photons reaching the plant

θ (λ)=spectral efficacy.

Thus θ (λ)=Y/E

Our objetive should be try to determine θ (λ) of different color mixes, and consider them together with other non photosynthetic effects, as flowering duration.

What ive seen is when using excess 660nm red light, flowering duration tend to go longer. While grows using shorter wavelenght of red, or directly amber, dont have such problem. Just by not using all 660nm, but half of red on shorter wavelenghts and adding some white avoid that problem.

Considering that phtosynthetic efficacy of isolated wavelenghts is almost constant from 610 to 675nm, IMHO makes little sense to insist using 660nm peaked LEDs. A possible enhancement about 5-10% is compromised by a longer duration of flowering, and may result on a reduced overal efficacy, because photons used are more during a longer flowering, lowering θ (λ). Aditionally, 660nm LEDs mostly runs about 665-670nm on operating conditions, sometimes still longer. That mean that part of the energy is emitted on longer wavelenghts which have reduced photosynthetic efficacy: there is a sharp drop on efficacy at about 685nm.

I think the question is if its profitable to use some 660nm LEDs together with shorter wavelenghts red and/or amber or directly not to use them at all.

Some of the trials currently running are using a mix of blue (470nm), amber (590nm), short red (630nm) and deep red (660nm). I believe there are 10 growers using this mix, some of them are currently starting the flowering stage. Ill report their results with the first harvest.

About the differences beteween strains, for sure they exist, but i wouldnt expect to affect too much. I upload some graphs of spectral differences of cannabis, depending of strains, stage of development and N feeding. Notice how they are mostly between a 3% range for most wavelenghts, except on the green. (it only alowws 4 attachments, i upload the most meangliful. They are copied from "Spectral Discrimination of Cannabis sativa L.
Leaves and Canopies", by C. S. T. Daughtry and C. L. Walthall)

 

[devilgoob]

knna, keep answering questions, the ones who are really smart wont be thinkin about lumens anymore.

they will think wavelength, ratios and umm FLUX CAPACITANCE....lol...whats the one im thinking...radiant flux? hmm

 

[knna]

The spectral output and longevity is my interest in leds, not power. Power will come with refinment and mainstreaming (not t say that leds will ever be so).

I only can agree with that for experimental purposes, meaning experimentation to find the most profitable color mixes.

But we never shlould forget that what most growers seek for when using LEDs for growing is electric savings. Any experimentation useful results will be about how to get the higher power savings. At the end, all is about about power (=electric bill).

We must try to find what mixes have the highest electric savings and discover if there are some type of trade offs between quality and quantitity. If so, and its reasonable to suppouse it, there wont be an "ideal" color mix for all, but growers must decide the color mix that gives the balance between production and quality they wish. I include any use of no PAR wavelenghts, as UV, on this category. Its not a priority for me, but im glad to see other people working on it.

When thinking on power savings, there is a question that very often is overlooked by LED's experimenters: differential efficiency of different LED's colors.

On a math expression:

E=P*e

where

E=amount of PAR photons

P=power burned (watts)

e=eficciency of the led (converting input power on light)

As i stated on my previous post, Y= E * θ (λ). As E depends of e, there are two main parameters determining yield from a given amount of watts burned: e and θ (λ), energy efficiency of the LEDs (e) and spectral efficacy of the color mix (θ (λ)).

So in order to design the highest electric saving array, its not only about spectral efficacy θ (λ), but too about energy efficiency. Say you get a spectral mix that gets a efficacy of 80% but it uses LED colors with an average efficiency of 20%. And another one that gets an efficacy of 75% but using LEDs with an average efficiency of 30%. On first case, you get a overall efficacy of Power (watts) of (0.8*0.2) 16% and on the second case, of 22.5%. Meaning that choosing the second mix with lower spectral efficacy is profitable because it will save more watts. Exactly, (22.5-16/16) of 40% less watts for same yield. A lot. As our main target is to being able to grow MJ with as less watts as possible, considering carefully energy efficiency of LEDs is a must.

Finally, i upload McCree and Inada curves of photsynthetic response vs wavelenght. They are experimentaly built curves of the response of terrestrial plants to isolated wavebands (2nm wide), so by far way more descriptive of how plants respond to light quality:

This is the Inada curve. It represent the photosynthetic response to equal amount of watts reaching the plant. So if you use Spectral Power Distribution graphs (SPD, that is a picture of how much watts a LED emits on each wavelenght), its the most accurate one to use. Use solid curve (1) for MJ, as 2 is for trees.

This is the McCree curve. It represent the photosynthetic response to a equal amount of absorbed photons for each waveband. This mean you cant use it to compare with SPD, but you need to transform watts to micromols of photons and after that derate it for each waveband absortion (MJ absortion is implicit plotted on previous post, as percentage of light absorbed is 100-(light reflected+light transmitted)).

As conversion between watts and micromols is direct when you know the wavelenght and MJ absorbance is known, it is possible to use the McCree curve with highest accuracy than Inada one to stimate yielding potential of a given spectrum. Its exactly what my spreadsheet does. But we need to explore sinergies between differents colors working together, that are not shown nor obvious at all. We only will discover them by experimentation.

I uploaded too the Phytochromes absortion graph. I want to show how 620-640nm orange/red light unbalance phytochromes equilibrium way less than 660nm, as i stated on previous post. Phytochrome equilibrium strongly affects flowering duration, phenotype expression and many other biologic caracteristics.

 

[jtk707]

I think led s have a long way to go , i was wondering if you guys thought on led lets just say the ufo for sake of argument , could a ufo support a bonsai mother plant? Thanks for the info peace

 

[billyjojimbob11]

Yes, it will support a mom, get a mostly blue ufo with little red.

 

[jtk707]

Thanks for the info bro

 

[billyjojimbob11]

Knna,

Knna, I think we all appreciate your input, your insight and knowledge on this subject. I would love to see the different results that you and you group have come up with. Please upload some photos of the results, as I am dying to see.

 

[HerbGlaze]

To me LED look really cool but whats the point?

HPS are almost 1/2 as cheap and grow faster and better plants, thats just my opinion.

 

[jtk707]

The point is in the near future we might all have a better light to use . This pot is getting everyone high whats the point of making a fruity cross

 

[Hal]

To me LED look really cool but whats the point?

HPS are almost 1/2 as cheap and grow faster and better plants, thats just my opinion.

The point is that the LED use much less energy (which can be used by LEO in their building a case against a grower), and more importantly, create only a small fraction of the heat that HPS do.

 

[billyjojimbob11]

billyjojimbob11, i think you forget the main one:

-Not enough light, of any PAR wavelenght.

I believe most LED grows that fail does it due to not using enough light.

I insist we need to consider the amount of light together with spectral quality. First, because we need to know the relative spectral efficacy of each color mix, and that is only possible comparing yield with amount of light used.

Consider the photosyntethic production as the result of multiplying the gross amount of PAR photons by the spectral efficacy of the color mix:

Y= E * θ (λ)

where

Y=yield

E=amount of photons reaching the plant

θ (λ)=spectral efficacy.

Thus θ (λ)=Y/E

Our objetive should be try to determine θ (λ) of different color mixes, and consider them together with other non photosynthetic effects, as flowering duration.

What ive seen is when using excess 660nm red light, flowering duration tend to go longer. While grows using shorter wavelenght of red, or directly amber, dont have such problem. Just by not using all 660nm, but half of red on shorter wavelenghts and adding some white avoid that problem.

Considering that phtosynthetic efficacy of isolated wavelenghts is almost constant from 610 to 675nm, IMHO makes little sense to insist using 660nm peaked LEDs. A possible enhancement about 5-10% is compromised by a longer duration of flowering, and may result on a reduced overal efficacy, because photons used are more during a longer flowering, lowering θ (λ). Aditionally, 660nm LEDs mostly runs about 665-670nm on operating conditions, sometimes still longer. That mean that part of the energy is emitted on longer wavelenghts which have reduced photosynthetic efficacy: there is a sharp drop on efficacy at about 685nm.

I think the question is if its profitable to use some 660nm LEDs together with shorter wavelenghts red and/or amber or directly not to use them at all.

Some of the trials currently running are using a mix of blue (470nm), amber (590nm), short red (630nm) and deep red (660nm). I believe there are 10 growers using this mix, some of them are currently starting the flowering stage. Ill report their results with the first harvest.

About the differences beteween strains, for sure they exist, but i wouldnt expect to affect too much. I upload some graphs of spectral differences of cannabis, depending of strains, stage of development and N feeding. Notice how they are mostly between a 3% range for most wavelenghts, except on the green. (it only alowws 4 attachments, i upload the most meangliful. They are copied from "Spectral Discrimination of Cannabis sativa L.
Leaves and Canopies", by C. S. T. Daughtry and C. L. Walthall)

True, I agree that fewer photons are a major problem with unsuccessful led grows, however, I think more important is how we are able to more efficiently direct the correct ratio of light with leds, thus, requiring less overall light. But I do think most of the problem is our lack of a broad spectrum red being used. For example, taking into account the Emerson Effect, which will not work without 2 colors of red, how are we to assume, without thorough testing, that flowering can be dramatically improved by using multiple red colors from 590-730 to balance out the effciency of the floweriing process.

Spectral distribution is so important in the flowering stages due to more processes within the plant taking place at the same time, less so than with vegging alone. To say that you can use a 630nm red to effectively and effeciently produce flowers is absurd, no matter how many photons you have. Sure, more photons, more intense lighting = more flowers, but how efficiently are you flowering with one narrow spectrum? Answer, not very!

To assume that flowers are just simple organism that only require intense narrow red and blue light is to assume a lot.

Using a spectral chart showing only, "plant response to light" with the obvious color peaks of efficiency is not the whole problem.
Plants make their own food, what light wave or waves are responsible for this? Can we assume that it is only 630 or 660 or 730? I think not.

The mechanics of plants, obviously in the flowering stages, are far more complex than just intense narrow wavelengths.
Success can be achived by using the colors that have proven successful such as 425-440 450-470blue, 635-660 red, but dont forget to fill in the colors in between. It is those colors, and the ratio thereof, that is keeping us from the overall success of led grows in my opinion, more so than just more photons.

Thanks
BJJB

 

[knna]

Notice that LEDs arnt pure monochromatic light sources as lasers, but cuasimonocromatic, meaning that the peak wavelenght we often refer to them only points out the nanometer at that the highest energy is emitted. But there is on the narrower cases a band of 20nm that emits at least half of that energy.

In fact a 640nm LED often emits from about 600nm (and sometimes, still lower wl) to 680nm (and still longer).

So we cover almost the entire red range. Thus the problem is to know is energy emitted on those other wavelenghts is enough. Its not about if use it or not, because we are giving energy on a relative wide bandwith independent of the LED used, but how much energy works best.

But we are limited to the use of only some different spectrums, as we cant order custom spectrum from manufacturers. So our problem is just to choose what works better for growing MJ.

Its possible that mixing different tones of red, as 645 and 660nm peaked LEDs works better than using just one of them. But then, we must determine the best ratio for using them. As LED's efficiency is currently changing, we need to know how much energy emits each LED we are using, so we can keep using the best ratio for whatever other LEDs used in the future.

And again, weighting the differential energy efficiency with the spectral efficacy is a must: if using 30% of energy from 660nm peaked leds gets an improvenment of light efficiency of 10% but at the cost of reducing the amount of photons per watt on 10%, we are not gaining anything from the added complexity. So talking about it does us advance very little. What we need is true experimentations, and being able to answer how much and comparative efficiencies. Not generically, but accuratelly measured, or it wont help us on nothing.

If i have something pretty clear is that plants lighting is way more complex that adding a few narrow wavelenghts. But to throw some light on it, about what spectral distributions works better, what of them are more profitable, and what trades off we need to take into account is on pure empirical research.

For lounge's talking, we have done it for years and it havent added almost anything.

 

[billyjojimbob11]

I think we totaly agree, however, covering the "broad spectrum" with light that accounts for less than 5% of total output, is not efficient and does not cover the amount needed. I agree that 660's are much less efficient than 625, especially when heated, but it should be in the mix to account for lower red wavelenghs that will still be lacking when only using 625's.

http://www.icmag.com/ic/picture.php?albumid=3016&pictureid=39020

Here we have the hps, which, uses more 575-650 than anything, dropping off sharply after 630, with most intensity at 586 and 598. Now, we know that hps is fairly successful in flowering, with obvious room to be more efficient (we could do without all the green). So using the binning process to make available leds to fill in areas that are not normally covered in with red and blue grow lights, I will set my sights on mostly 585-620 which I believe will use on a mostly even ratio, against 625's.

My array eventually should look similar to this:

585-591 x 3
591-595 x 2
610-620 x 5
620-630 x 10
660 x 2
735 x 1

440-445 x 1
465-470 x 1

I also think hope that 11.5 x 1 red to blue will be effective.

Knna, have you purchased any of these Edixeon in respective bins?

 

[knna]

Knna, have you purchased any of these Edixeon in respective bins?

No, finally i havent. Really im getting way better price and efficiency from 640nm LEDs than from 660nm.

Im very interested on playing with the far red Edixeons, but i dont feel it a priority. Ive noticed that they arnt strictly needed, although they may be very useful helping in the control of plants. But they seem of need when using 660nm light and no white, to avoid lastening the flowering induction period and keep flowering duration even with other light sources. As now i know that using shorter red wavelenghts and adding white solves the problem, im now concentrated on finding the best PAR spectrum distributions. So ill wait for experiments with non PAR wl (UV and far red).

But I can get them at good prices, better than the little shops selling them. If enough people are interested on them, i can order them.

About your spectrum mix, the number of LEDs used alone dont gives enough info. They all are going to run at same current? How much efficients are they?

One thing is sure, you want get any lacking along the orange-red part of the spectrum. If they all gives similar amount of light, you are going to get a continous spectrum from 570 to 750nm, peaking at about 630nm.

But talking about lackings, from 490 to 560nm you havent any light. Its the range of carotenoids absortion, which are important in flavor and photoprotection. I really dont know if adding light on that range is needed for having carotenoids working enough, but if you are trying to get an spectrum without lackings, i think you should add some cyan to that mix.

 

[billyjojimbob11]

Yes, I think I will add 1 3000k warm white to the 21 watt mix. I found a chinese company that uses some fairly good leds and I will put them in a 21 watt down spot light with narrowing lenses. I will order several different 21 watt arrays for testing.

Please, if you have a 21 led request, let me know the combination and I will test.

Effeciency of the leds is not what I am testing, only testing color mix. So I will may double (42 watt) on small clones in cups from same mom and see what flowers fastest.

BjjB

 

[billyjojimbob11]

Hans at ledgrow.eu apparantly has just come to the conclusion that white, I assume he uses neutral or warm white, has prevented the delay in flowering. As more evidence that the broader spectrum is very important, but using to many whites is inefficient.

Maybe it is Cyan, some green.

 

[knna]

but using to many whites is inefficient.

That statement was right just until now. But currently, top bin coolwhites released have same, and still superior, efficiency than red LEDs. In terms of photons per watt burned, they are currently at same level. Talking about PAR watts emitted for each watts burned, currently whites has surpassed red ones.

Its due the emphasis of all main LED manufacturers on developing white LEDs, that led AlInGaP tech (of reds) sttoped since some years ago.

Currently, comparing top end LEDs, blue chips are more efficients than red ones. At the point that currently may have sense to use a blue chip to emit red light, by converting through phosphors. As this trend continues probably in the near future its going to be possible to do it profitably. But we have a wider range of phospors for LEDs than for fluorescents, and that does possible to build fine tuned white spectrums covering the full range PAR just using blue chips.

As noted previously, without knowing the enrgy efficiency and quantum efficiency of each LED, its diffucult to say what is batter.

 

[billyjojimbob11]

Yes! that makes sense. Little new development has gone further when developing colors efficienty. Quantum dotting phospher will most likely be the breakthrough in household led this year, hopefully we will see some highly efficient white leds.

I say, maybe if we are going to use a light for flowering, you should just use various whites along with the most efficient red and amber cree's, or Phillips.
I mean, blue is hardly needed right?, and we would be getting plenty with the white leds. So that could be one avenue for improved efficiency. Im thinking, 2400k would be an ideal led if efficiency was good, 3000k is fine, mix in a little red and amber, pop on some lenses, spred leds out on Aluminm sheet with mounted fan on top, fire up at 1000ma, and PRESTO!!!
GIGANTIC LED BUDS!!!!

I am seeing very little improvement using Led+Halogen
More improvement using Led+3200kCFL

White will cover any blue green or yellow green light needed, but is it as efficient as using green ZnO/GaN material? Probably not. So it keeps going back to: what colors do we need first? Then work on efficiency afterwards.

Leds do not have to be more efficient than HPS, just needs to be as efficient.

Should we forget the blue's and use whites in their place? I mean for flowering only...