CRI test and Mcree weighted results

[wietefras]

Actually I read a thing the other day saying that you can use green light as a night break to prevent flowering. They said green or red. So the thing about using green to look around during the dark period is rather questionable. Probably wouldn't notice unless you did it about 8 hours into the dark period, when a night break is most effective. That must be why people have been getting away with it this long, just lucky timing.

It's not just lucky timing, it's related to the absorption spectra of Pr and Pfr phytochromes:


As you can see, between 400nm and 500nm the Pfr line is above the Pr line, so for those wavelengths there is no danger of breaking the flowering cycle. Similar to wavelenghts over 700nm. Or go for 500nm exactly where the Pr is lowest.

Although it's also clear that you should be carefull with what type of green light to use. If it's really bright green (around 550nm) then there might be an issue Although you'd need to have that light on for a long time and/or high brightness. Red light in the 660nm area is much quicker to switch to non-flowering.

 

[NoFucks2Give]

. If other pigments such as

Again good work.

I have an open mind towards green. I have no issues with using white CoBs to grow plants, they work very well.

As far as the green hole syndrome (green window), there is not a scientific consensus on the topic. If I had to chose today I would have to go with the green hole. More scientists agree with the green hole/window.

In the above quote,l like so many of the pro green statements there is too often an "if" If other pigments...

At the university I get to see many of the results from experiments. Most experiments are not published. Many times all I get to see is a photo on someone cell phone.
The latest I say was roots exposed to red light compared with normal roots on Colquhoun's phone, he was really excited. The red roots were shorter and thicker than the normal roots. The plan is to set up a hydroponic sytem using 4" clear acrylic pipe.

Whenever a new spices is going to be used in an experiment it goes in to a grow chamber with 4 separate isolated red, blue, green, and amber LEDs. EVERY spices under the green come out looking like shit. Except seedlings.

We got just lucky enough .

You cannot go wrong with the Sun. It's worked pretty well so far. But there is the unanswered question Is the sun's spectrum the ideal spectrum for plants? It is cheap. But if you had to pay for it, would it be the correct spectrum.

This image is from one of my favorite studies.




The RBFr looks elongated as it should by activating Shade Avoidance Syndrome.
The GH has the most mass but looks a bit scraggly.
I kind of prefer the RBY. Who uses RBY?

The GH is Green House grown in the Florida Sun in July. So it may be possible to find something superior\r to the sun. Research is very slow.

BR is nothing to write home about. My stand on BR is its efficiency in feeding the plant photons. It is NOT the only two wavelength I use. I do NOT use green. I may try green for seedlings. But I like the blue yellow for seedlings. From Plant Physiology and Development:

There are several ways to experimentally separate a
reduction in elongation rates mediated by phytochrome
from a reduction mediated by a specific blue-light response.
If lettuce seedlings are given low fluence rates of blue light
under a strong background of yellow light, their hypocotyl
elongation rate is reduced by more than 50%.
The back-ground yellow light establishes a well-defined Prfr ratio
(see Chapter 17). In such conditions, the low fluence rates
of blue light added are too small to significantly change this
ratio, ruling out a phytochrome effect on the reduction in
elongation rate observed upon the addition of blue light.

 

[wietefras]

It NIST that proposed to not use the sphere for LED measurement in favor of a radiospectrometer. It was NIST that proposed the Flux Intensity setup adopted by CIE.

No, they didn't. Those quotes only say that for leds a sphere might not be strictly needed and that a "geometry measurement" can suffice. Which means a goniometer and not a spot measurement, nor that they imply that intensity is what's measured. They still measure flux (by taking may spot measurements and using the geometry to calculate total flux).

 

[stardustsailor]

Be careful here .
Leafy greens like the ones in the pic have way different energy needs than flowering / fruiting plants.
Leafy greens can be grown with several monochromatic LED combinations
(depends on the wanted results i.e rich in antioxidants or broad leaves or ,or ..)

But when it comes to light -needy plants ...
Then you can try whatever light combination without green.
None is going to be as productive as plain white light .
None.
If you do not trust / believe me ,then all you 've to do is actually try it.
Experiment with .
I'll be waiting for your results.

 

[BobCajun]

I tried a green reducing light filter for a while and all I got was a lot more bottom leaves dropping off. Apparently those bottom leaves rely on the green that gets through. So people using red and blue LEDs could have the same issue. Neither red nor blue can penetrate far at all. I guess an alternative would be to add bottom lighting with the red and blue, but who's gonna go that far?

 

[wietefras]

As far as the green hole syndrome (green window), there is not a scientific consensus on the topic.

Bullshit.

Where do you think the definition of PAR comes from? It's a simplifcation of the McCree RQE. Why do you think they use YPF to be even more accurate than PPF?

Seriously, stop it already.

 

[NoFucks2Give]

As you can see, between 400nm and 500nm the Pfr line is above the Pr line

There are six genetic pathways to transition a plant into flowering.

The problem with most RFr application is it is a ratio of red to Fr. Your lighting must be adjusted to the correct ratio.

The consensus on using a light in the dark cycle is DO NOT EXPOSE the plant to light. Far red can be briefly turned on at the beginning of the dark cycle but photoperiod works well enough.

The attached paper shows the results from a shit load of the studies. On page 13 it discuses flowering. It's a nice paper it covers many topics regarding R:Fr.

Is it possible the reason someone suggested to use green in the dark cycle is because it is not utilized very well? Of course it would be incorrect to ignore phytochrome-mediated regulation with green. Just keep it dark.

 

[Sativied]

Ffs still discussing green light against while they still don't get the difference between relatively and absolute.

One thing I've to say to you: Half knowledge is worse than ignorance

Wow...
https://www.amazon.com/Best-Sellers-Home-Kitchen-Handheld-Mirrors/zgbs/home-garden/3736391

@NoFucks2Give: you are wasting your time here with these intellectual dishonest parrots. You can post a million facts and valid arguments backed up with authoritative resources but it won't change a thing. They confuse knowledge with parroting utter nonsense that once parrotted has to remain true for religious and ego purposes. Nonsense that has been inbred so much over the past years it spawned some proper retards.

In the rare scenario where you might activate some brain cell in one, another will quickly dismiss it as not applying to cannabis because it's special magical plant, or will claim the absense of specific cannabis related research that spells it out for them means proof of absense as well. And if it does exist, they will conveniently give their own interpretation to a few picked cherries.

Unless you want to practice recognizing all the classic fallacies... run, it's a trap.

 

[NoFucks2Give]

add bottom lighting with the red and blue, but who's gonna go that far?

I am currently working with the landscape architect at 220 Central Park South. $5,000 per sq. ft. condos in Manhattan.

I sent them a prototype 12" strip of 16 white LEDs. Why white? They want a natural look in their words "not like a Christmas tree". I am not that stuck on mono LEDs.

The lights are adjusted to proved between 130 and 150 µmol/m²/s

The building is shaded from sunlight. Typicality the landscape guy replaces plants and tree about every five years in cases like this.

There are a number of studies using inter-canopy lighting. I attached one study. This one may be a McGill University in Canada. There are two US universities do research into inter-canopy lighting. I think it would be a very efficient way to provide photons. If it works.


.

 

[NoFucks2Give]

Where do you think the definition of PAR comes from?

What does that have to do with the efficiencies of particular bands of PAR wavelengths. I am not saying green does not work, just that green is less efficient that red or blue. I don't have any problems with using white. It is something to consider. Do as you please. Ignore the science. I do not give a fuck.

 

[NoFucks2Give]

No, they didn't.

In many applications, however, backward emissions, or even sideway emissions are not useful, and the flux emitted only
in a limited solid angle may be meaningful. For such a purpose, a new quantity, Partial LED Flux is proposed,

NIST said:
If you find it necessary to measure total flux, do as you please I do not give a fuck. I prefer to use ""Partial LED Flux" as proposed by NIST and adopted by CIE 127.

 

[NoFucks2Give]

Unless you want to practice recognizing all the classic fallacies

I hate that logic fallacy stuff. The scientists always like to throw them around.

I am actually here doing research into the problems with grow lights. There is a treasure trove of misinformation here.
I find these naysayer guys humorous.

I may have found a way to explain why their shit does not work in simple enough terms for even the likes of even @wietefras can understand rather than pretend to understand.

My user name on this site was chosen just for these guys I call the CoB Snob Bullies. They drive away anyone with intelligence so they can reign in ignorance. I like a challenge. You are not the first to suggest I give up on them.

Thanks for the support.

 

[stardustsailor]

What does that have to do with the efficiencies of particular bands of PAR wavelengths. I am not saying green does not work, just that green is less efficient that red or blue. I don't have any problems with using white. It is something to consider. Do as you please. Ignore the science. I do not give a fuck.

Exactly !
But that does not automatically excludes it from being necessary .
If not obligatory in certain cases (say like under powerful artificial lighting ) .
Typical efficiency of photosynthesis is 2% .
By not supplying green light , efficiency drops way less than 2% .
There's no way by altering the four light variables ( quantity-quality-duration-direction ) to
increase that efficiency .
You think that by providing the more /most absorbable and /or efficient parts of the spectrum ,
the photosynthetic efficiency would increase ?
There are so many "counter-acting " effects and reactions that would take place against .
Nope.I'm afraid it won't at any possible case.
You can only decrease it.

Please search for a paper that even indicates that this is feasible.

There's no magical spectrum.
What plant's are genetically "prepared" (after some millions years of evolution ,note that -it has its importance )
to harvest as "best form of energy " is sunlight .
Aka a "balanced " mix of UV -Blue-Green-Red and FR .
With the green part being the most abundant ,energy-wise.

Alter firstly the genome (thus the physiology and biochemistry ) of the plants in order to make them
absorb and utilise light more efficiently than 2%
and then use an (electrically ) efficient light with it's spectrum accustomed to the genetically modified plants.

Otherwise ,introducing new forms of energy to simple organisms that follow simple "rules"
which in turn are dictated from a million years background of collected information ,ain't gonna work .
Actually is something like ....
Trying to teach new tricks to an old dog .

Cheers.

 

[Stephenj37826]

But you did not do the math. You talk about wall watts in, yet nothing about radiant watts out, thermal watts out, or quantum efficiency.

So you think 200 lm/W is high efficiency for green? It's twice as good as what is currently being sold. What is done in the lab is one thing. What is economically feasible to mass produce is another. Currently the green LEDs being sold by Cree, Lumileds, and OSRAM are native green, not phosphor. While some green phosphors may be more efficient at producing photons, they are not yet economically viable for mono LEDs. White LEDs have to use green phosphors.

The only common mono LED color being sold is PC Amber. I have never seen a PC green LED.

Can we agree that a direct narrow band deep red and deep blue are more efficient than a phosphor pushed red and blue? Deep blue is the no brainier because they are used in white LEDs except covered with phosphor. The white paper I posted from Lumileds says direct red is more efficient than red phosphor. With red it's a matter of economics whether to use mix technology where a direct red produces superior CRI with phosphor blue and green vs. RGB phosphor.


So if we were to make a grow light using mono RGB that produce 5 µMoles each of red, green and blue. How efficient would that be? It will be more efficient than a phosphor pushed RGB, correct?

The efficiency 36.6% using the most efficient Red Green and Blue LEDs on the market calculated at their Maximum rated output run at their most efficient current at an unrealistic 25° C.

And that is why I do not believe a CoB is 60% efficient.

Let's do the "simple maths"

Currently the most efficient on the market

Cree XP-G3 Royal Blue .730 radiant Watts @ 350mA 2.82V,
Cree XPE green 113 lm/W @ 350mA 3.2V,
OSRAM Olsen SSL Hyper Red .530 radiant Watts @ 350mA 2.15V

To produce 5 µmol each of RGB we will need 2 blue 1.8W, 5 green 5.7W, and 2 red 1.7W.
Datasheets attached so you can check the "simple maths".

The column lm/W is the number of lumens required for 1 Watt radiant flux.
The column µmol/W is the number of µMoles in one watt radiant flux at that wavelength.
flux is in watts

View attachment 3966939

Efficiency of 36.6% so 15.02 umol for 9.24 watts or 1.62 umol/j.... Not sure if you included driver loss or not but that number even at system level is nothing to brag about. White phosphor conversion is well into the 2+ umol/j range and the best part....... It's much cheaper than high power mono in most cases.

 

[BobCajun]

You can actually grow plants under pure green light and the yield is only slightly reduced. Green always produces the least dry plant weight, but it's not as drastic as you might expect from the chlorophyll graph, like maybe 5% reduction.

 

[NoFucks2Give]

I had a hard time hitting the post button on this but I could not leave a could of things unaddressed.
I like you but I did not like some of your comments.

Alternatives ?

Deep Red with great thermal management.

And a phosphor pushed green LED ain't ?

That is correct, it ain't. I may have been wrong about the less than 10% it is getting closer to 20% which is still dismal.
I understand there is green phosphor. But no one is selling mono green phosphor pushed LEDs that I know of. I am still looking.
I am expecting red phosphor mono LEDs to begin surfacing some day soon. I did see one other color besides PC Amber, I do not remember the wavelength.

Like that "official " chlorophyll absorption charts are more or less useless ,
'cause they used extracted chlorophylls into organic solvents (with the latter having their own absorption /reflection spectra and "contributing" to the -way false/ skewed - results also) and they did not use alive plant tissue ,where BTW you can find plenty of light-harvesting proteins

Hmm. Let's see, scientists all around the globe think the chlorophyll absorption charts are valid. You do not. Who should I believe?

Otherwise ,is almost certain that quite a few people around here
by reading your posts ,unavoidably all they can think is : "OMG ,that guy is full of shit ! "

Ditto.

Much less I would have said for light > 730 nm

Is that why PAR cuts off at 700nm?? Cool.

"The plant does not care if a photon is green or red, they are equally utilized. "
For photosynthesis more or less it might be true .
But what about phototropism ,circadian rythms and photomorphogenesis ?
They are not "out of the whole picture" at all , as you may know about.

I'm an engineer programmer not a plant physiologist. I have read about phototropism ,circadian rythms and photomorphogenesis bu tI do not have any reason to know that stuff. And it's hard to understand without a PhD. I'll leave that for the experts that enjoy that sort of stuff. If they need an LED grow light for their work I'm there to provide it. I just want to feed my plants some photons without paying an arm and a leg for them.

it's all about simple maths and basic semiconductor physics.

This one still floors me. Simple maths? What was that phrase?? Oh, okay, found it: "OMG ,that guy is full of shit !

Got some simple maths for converting lux to watts or ppf or back the other way? I do. I'll show you mine if you show me yours. My guess is you are clueless and are pretending to know how to do this stuff. Prove me wrong, show me. Or just tell me in the spreadsheet what is the column labeled "Energy per mole" is for. That should be good for a laugh.

 

[BobCajun]

Looks like using purple instead of blue for phosphor coated LEDs increases wall plug efficiency to about 84%. The article also said they were more costly though.

"Purple LED chips are usually triangular, compared to normal LED chips rectangular shape. The triangular purple LED’s luminescent layer has better light emittance compared to square shaped LEDs. Due to purple LEDs high crystal quality and good light extraction efficiency, its wall-plug efficiency (WPE) can reach 84%. Average blue LEDs WPE in general is between 50% to 60%."
http://www.ledinside.com/news/2015/8/purple_leds_to_replace_blue_leds
http://www.ledinside.com/news/2015/8/purple_leds_to_replace_blue_leds

 

[NoFucks2Give]

Typical efficiency of photosynthesis is 2% .
By not supplying green light , efficiency drops way less than 2% .

Citation?

 

[BobCajun]

Green does help but only if it's up to 25% of the red/blue/green. Above that it apparently has a negative effect. Don't have a reference at hand but it's easy to find if you search about green light and photosynthesis, I would think. That's how I found it. BTW blue light is beneficial up to 50%. So in reality you wouldn't need equal amounts of red, blue and green, but slightly less green. Whether or not it's practical, considering the varying efficiency etc, is debatable. Ideally though you should have some green, if only for a healthier lower canopy.

 

[NoFucks2Give]

Efficiency of 36.6% so 15.02 umol for 9.24 watts or 1.62 umol/j.... Not sure if you included driver loss or not but that number even at system level is nothing to brag about.

I agree. My point was that mono LEDs are more efficient than CoBs. Previous to that I posted documentation to support the hypothesis that LEDs are more efficient than CoBs. Case in point, if CoBs were more efficient, they would be selling phosphor pushed mono LEDs.

No I did not include driver loss. I even used pie in the sky characteristics from the datasheets. No thermal degradation,, 25° C. Max possible theoretical numbers. With those parts there is no way the results could be reached in a real life application. And if there wer a CoB that could do 5 µMoles of Deep Red Green and Blue

.. It's much cheaper than high power mono in most cases.

That is very debatable. I think I could put up a good argument for either side of that argument. Good point.

The cost of the LEDs is not that important when the cost is easily recovered in short term ROI. Five year return is pushing it. One to two years is economically viable.

Someone once asked to comment on ChilLED. I went off on them because of their comments on Watts and other things like their dysfunctional website not related to the quality of their fixtures.

I was recently searching for something and ran across their site again. I was very impressed with their detailed design. I even liked their choice with the Dow Corning TIM, so much I'm going to try it. The design of the dual use ducts is ingenious. Their optional water cooling is very neat and clean. Very flexible design.

The only issue I see is who can afford that expensive cabinet, duct work, or cooling maifold? The numerous pieces of sheet metal has to be a nightmare on inventory costs. What good is a technology if no one can afford it? Steve Jobs NeXt cube come to mind. He was good at turning shit into gold. He turned the Cube into a hefty share of Disney via Pixar.

I think the holy grail of an LED fixture that cost less than an HPS with superior performance is now viable. I liked the Cree Horticulture Reference Design. I think it is a horrible design as far as being economically feasible. But it showed how many LEDs are required to match a Gavita Pro HPS. And on that note I think Cree may be bowing out of horticulture. I saw on Digikey they discontinued their XP-E Photo Red 660nm with no 660nm substitution in place.