# The Importance Of Light Spectrum



## jaypeecee (7 Feb 2021)

Hi Everyone,

If you were ever in any doubt about the importance of light spectrum, please take a look at the following:









						Blue light reduces photosynthetic efficiency of cyanobacteria through an imbalance between photosystems I and II - Photosynthesis Research
					

Several studies have described that cyanobacteria use blue light less efficiently for photosynthesis than most eukaryotic phototrophs, but comprehensive studies of this phenomenon are lacking. Here, we study the effect of blue (450 nm), orange (625 nm), and red (660 nm) light on growth of the...




					link.springer.com
				




Although the document title gives the impression that blue light and cyanobacteria are being spotlighted (pun intended), there is a wealth of information in this paper. In particular:

"Engelmann continued his studies with cyanobacteria from the genus Oscillatoria, demonstrating that in these cyanobacteria, not only red and blue light but also orange light resulted in high O2 production rates (Engelmann 1883, 1884). Engelmann’s findings were criticized for many years, but 60 years later, his results were confirmed by Emerson and Lewis, who showed that the phycobiliproteins of cyanobacteria and red algae play a key role in light-harvesting for photosynthesis".

I have often been concerned that light at some wavelengths may promote algae and/or cyanobacteria - orange light at 625 nm in particular. Many aquarium lighting products have substantial output at this wavelength. I prefer to see products with output at 660 nm corresponding to the peak response of chlorophyll b. And at the blue end of the spectrum, 450nm for chlorophyll a. Oh, yes, and a good helping of green!

JPC


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## Paulthewitt (7 Feb 2021)

Are you able to put a summary in peasant Anglian for those of us who cannot understand it please? 😂

I’m particularly interested in the blue light as I have covered mine up as the cooler light looks weird and I heard algae thrives more on it?


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## jaypeecee (7 Feb 2021)

Hi Folks,



jaypeecee said:


> I prefer to see products with output at 660 nm corresponding to the peak response of chlorophyll b. And at the blue end of the spectrum, 450nm for chlorophyll a.



I need to check the accuracy of my two sentences above. But that will have to wait until tomorrow. This in no way changes the importance of the cited paper.

JPC


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## jaypeecee (7 Feb 2021)

Hi @Paulthewitt 



Paulthewitt said:


> I’m particularly interested in the blue light as I have covered mine up as the cooler light looks weird and I heard algae thrives more on it?



It's possibly not such a good idea to cover the blue light. Both ends of the photosynthetic spectrum - blue and red - are particularly important to plants. Are you using fluorescent tubes or LEDs? If the latter, is your lighting dimmable?

JPC


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## oreo57 (8 Feb 2021)

I see nothing applicable to eukaryotes i.e normal algea and plants. 
To point to one difference:








						Effects of light of altered spectral composition on coral zooxanthellae associations and on zooxanthellae in vitro - Marine Biology
					

Pocillopora damicornis (Linnaeus) and Montipora verrucosa (Lamarck) were collected from Hawaiian reefs. In two experiments (September 1979-January 1980: ca. 4 mo; August-October 1980; ca. 2 mo), these reef corals were grown under sunlight passed through filters producing light fields of similar...




					link.springer.com
				



The in vitro cultures of zooxanthellae from M. verrucosa exhibited growth rates in light of altered spectral quality that correlated with the responses of the host coral species: blue and white light supported significantly greater growth than green light, and red light resulted in the lowest growth rate.


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## alto (8 Feb 2021)

oreo57 said:


> I see nothing applicable to eukaryotes i.e normal algea and plants.


all the references to Chl _a_ 


I thought the point of the post and interest of the paper was in regards Cyanobacteria which are present in many aquariums 
(I don’t know of too many freshwater Aquariums with zooxanthellae)


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## oreo57 (8 Feb 2021)

alto said:


> all the references to Chl _a_
> 
> 
> I thought the point of the post and interest of the paper was in regards Cyanobacteria which are present in many aquariums
> (I don’t know of too many freshwater Aquariums with zooxanthellae)


Blue green algae is effectively cured/contained w/ antibiotics.
Personally in over 4 years cyano has been the very least of my worries..
Even results between prokaryotic species is err "complicated".


> The specific growth rate of _C. sorokiniana_ did not change with the percentage red light. In contrast, the specific growth rate of _Synechocystis_ strongly increased with the percentage red light, up to 65% red light, and then gradually saturated


Point was it's risky assuming effects from one species to another much less from one phylum to another.
zooxanthella use chl a and c but are more closely related to normal algae than any procaryote.






> Although the document title gives the impression that blue light and cyanobacteria are being spotlighted (pun intended), there is a wealth of information in this paper.


Seems you were implying "spreading out" your conclusions. If not, my mistake.

now as to spectrum being important a consideration of the Emerson effect on photosynthetic higher organisms would be interesting.
The whole PSI/II thing is complicated.
Not to mention the issues of results using monochrome lighting in small numbers unlike most aquariums whose spectrum (even w/ RGB) is much wider.







						How It Works
					

Lear about the emerson effect and how its effects on photosynthesis can reduce growing times and increase crop yields through light manipulation alone




					aigrowlight.com
				




Bottom line for me personally is chasing tweaks of spectrum for algae control seems to be a very difficult endeavor if not completely fruitless.
I am open to be proven wrong but never saw anything that was helpful or easy to implement.
The whole PSI/II thing is complicated as is saturation point effects.
Better to maintain a healthy well balanced environment than worry about tweaking the spectrum.

Heck one can adj. growth rates using temp too




Thanks for the paper, I like to post them myself on occasion.

In case you are wondering and to sum it up a bit. I don't think you're wrong per se but see little usable utility in it.

Pick your spectrum. BTW supports your hypothesis but can you actually see a practical use for it?













						Colorful niches of phototrophic microorganisms shaped by vibrations of the water molecule
					

The photosynthetic pigments of phototrophic microorganisms cover different regions of the solar light spectrum. Utilization of the light spectrum can be interpreted in terms of classical niche theory, as the light spectrum offers opportunities for niche differentiation and allows coexistence of...




					www.nature.com
				





> They developed a competition model that predicts that red picocyanobacteria should become dominant in green light, green picocyanobacteria should become dominant in red light, whereas red and green picocyanobacteria can coexist in the full spectrum provided by white light. The results of their competition experiments were consistent with these predictions. These studies demonstrated that light color plays a decisive role in the species composition of phototrophic communities, *at least in controlled laboratory experiments.*


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## dw1305 (8 Feb 2021)

Hi all.


oreo57 said:


> Blue green algae is effectively cured/contained w/ antibiotics.


We don't have access to antibiotics in most of Europe, which I see as a <"plus point for human health">, even if it restricts what we can put in our aquariums.


oreo57 said:


> Bottom line for me personally is chasing tweaks of spectrum for algae control seems to be a very difficult endeavor if not completely fruitless.


That would be my thought as well. It is back to the same sun over the last 4.5 billion years and <"the likelihood that all photosynthetic organisms have a common ancestor">.  

You can ignore the non-photosynthetic bacteria, so "*d" * & "*e" *are what we are interested in and I'd say "_what is sauce for the goose is sauce for the gander"_.

cheers Darrel


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## jaypeecee (8 Feb 2021)

alto said:


> I thought the point of the post and interest of the paper was in regards Cyanobacteria which are present in many aquariums


Hi @alto 

Yes, my apologies. I wasn't at all clear what prompted me to start the thread, was I? I should have gone to bed and left it until this morning! In previous UKAPS discussions about aquarium lighting, the emphasis (understandably) has been on providing the 'right' spectrum for the plants themselves and viewing aesthetics. But, I have long been concerned about the impact of lighting on algae and cyanobacteria. This paper addresses both of these. It is heavy-going but it's worth persevering with it - in my opinion.

JPC


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## jaypeecee (8 Feb 2021)

oreo57 said:


> Seems you were implying "spreading out" your conclusions. If not, my mistake.


Hi @oreo57

Sorry, you've lost me there.



oreo57 said:


> Personally in over 4 years cyano has been the very least of my worries..


That may be your experience but take a look at the sheer number of people on UKAPS that have problems with cyano - myself included. BTW, I am _very_ much aware of other factors that contribute to the blue-green menace and algae - particularly dissolved organic matter (C and P).



oreo57 said:


> Bottom line for me personally is chasing tweaks of spectrum for algae control seems to be a very difficult endeavor if not completely fruitless.


If aquarium lighting incorporates LEDs matched to the absorption/action spectrum of plants, then one has a good starting point. Some manufacturers provide just this. Then, it's a simple matter of adjusting the intensity of these LEDs accordingly. It's not rocket science. This is PAR (!) for the course with hydroponics, horticulture and agriculture.

That's enough for now.

JPC


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## dw1305 (8 Feb 2021)

Hi all, 


jaypeecee said:


> But, I have long been concerned about the impact of lighting on algae and cyanobacteria. This paper addresses both of these. It is heavy-going but it's worth persevering with it


What about light intensity? (From <"Blue light reduces photosynthetic efficiency of cyanobacteria through an imbalance between photosystems I and II">) You would need a PAR meter and also to have enough light for your plants and too little for your BGA.






I'm going to assume this the bit (in <"Colorful niches of phototrophic microorganisms shaped by vibrations of the water molecule">) that has interested you as well?


> _......... Peaks in the underwater light spectrum at wavelengths below the sixth harmonics (<514 nm) are captured by chlorophyll a and b, divinyl-chlorophylls a and b and accessory carotenoids. The peak in the underwater light spectrum between the sixth and fifth harmonics (514–604 nm) is captured by the phycoerythrins of red algae and cyanobacteria. Peaks in the underwater light spectrum between the fifth and fourth harmonics (604–760 nm) are captured by phycocyanin, chlorophylls a, b and d.........._


I still think that there is too much of an overlap in the spectra of "*d" (*BGA*) *& "*e"  *(Red Algae, Green Algae, Higher Plants, Diatoms and Chrysophytes). 

This graph (from "Blue light reduces........") shows what I mean.





_Light absorption spectra of the cyanobacterium Synechocystis sp. PCC 6803 (black line) and the green alga C. sorokiniana 211-8K (grey line) acclimated to 35 µmol photons m−2 s−1 white light._



jaypeecee said:


> If aquarium lighting incorporates LEDs matched to the absorption/action spectrum of plants, then one has a good starting point. Some manufacturers provide just this. Then, it's a simple matter of adjusting the intensity of these LEDs accordingly.


There is a practical solution if you want to experiment, you can get Blue/Red LED arrays for Hydroponics. They give you more "bang for your buck", but have a very low CRI and you may not be able to find spectra for them. 

cheers Darrel


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## jaypeecee (8 Feb 2021)

Hi @dw1305 



dw1305 said:


> What about light intensity?


I didn't mention this because I (wrongly?) assumed that it would obviously have a positive correlation with algae growth. 



dw1305 said:


> I still think that there is too much of an overlap in the spectra of "*d" (*BGA*) *& "*e" *(Red Algae, Green Algae, Higher Plants, Diatoms and Chrysophytes).



I'm not sure about that. It is easy to select LED devices with centre wavelengths that differ by only a few nanometres (nm).



dw1305 said:


> There is a practical solution if you want to experiment, you can get Blue/Red LED arrays for Hydroponics. They give you more "bang for your buck", but have a very low CRI and you may not be able to find spectra for them.



I generally buy LEDs from the likes of RS Components who also provide manufacturers' published data.

JPC


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## Paulthewitt (8 Feb 2021)

jaypeecee said:


> Hi @Paulthewitt
> 
> 
> 
> ...


Thanks - I will uncover. It’s led with electric tape over the blue leds.

Couple of other useful and simplified replies here were helpful too - thanks all


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## ceg4048 (9 Feb 2021)

oreo57 said:


> Bottom line for me personally is chasing tweaks of spectrum for algae control seems to be a very difficult endeavor if not completely fruitless.
> I am open to be proven wrong but never saw anything that was helpful or easy to implement.
> The whole PSI/II thing is complicated as is saturation point effects.
> Better to maintain a healthy well balanced environment than worry about tweaking the spectrum.


Thank you. This has been our position for over a decade. In our particular tank environment BGA is neither triggered by the availability of orange/red light and will not be suppressed by the substitution of monochrome blue light. Clearly, the study did not demonstrate that the growth rate using blue light was zero, only that it was less than that of orange/red. Good tank husbandry, minimizing excessive PAR intensity, frequent and large water changes, clean filters and careful attention to CO2/nutrients (especially NO3) is the wisest course. Blue light will never save you from poor attention to the more important details of tank husbandry.

Cheers,


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## alto (9 Feb 2021)

ceg4048 said:


> In our particular tank environment


Sure I’m not the only one Curious what tanks you’re running these days?


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## ceg4048 (9 Feb 2021)

alto said:


> Sure I’m not the only one Curious what tanks you’re running these days?



Hi alto,
           I drained my tank while I was very ill for quite a while, and no way I could do my water changes (and you know how fanatical I am about that) but it's the same 200 gallon that I  just let run wild as a dry start - or maybe a dry end? It's just sitting there with the programmable lights running - 2 years - a real bummer mate.

Cheers,


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## alto (9 Feb 2021)

Sorry to hear that 
hope you’re doing better ... now imagining a 2 year old 200 gallon dry start jungle


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## jaypeecee (9 Feb 2021)

ceg4048 said:


> In our particular tank environment BGA is neither triggered by the availability of orange/red light and will not be suppressed by the substitution of monochrome blue light.


Hi @ceg4048 

You may be correct but what (scientific) evidence do you have to back up your statement? I'd also like to pick up on your word 'triggered'. I don't see it as necessarily 'triggered'. Isn't it a case of orange light at 625nm having the potential to 'feed' cyanobacteria with light of the very wavelength that it is well-equipped to utilize? Red light at around 660nm is needed by plants as it corresponds to one of the absorption/action peaks of chlorophyll a - as I'm sure you are very much aware. So, red light is here to stay. The other chlorophyll a peak is at 430nm give or take a gnat's whisker. This is at the blue end of the spectrum and, according to Dr Bruce Bugbee*, is very much needed but, in his words, 'shrinks plants'.

I know from previous posts that discussions about lighting can get somewhat 'heated'. Let's try to prevent this.

* Apogee Instruments

JPC


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## dw1305 (9 Feb 2021)

Hi all,


dw1305 said:


> This graph (from "Blue light reduces........") shows what I mean.
> 
> 
> 
> ...


I still can't see where there is enough difference between the two light absorption curves? The green algae are photosynthetically identical to higher plants (the form a clade <"the "Viridiplantae")>, so that would be the same for higher plant, fern or moss.

cheers Darrel


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## jaypeecee (9 Feb 2021)

oreo57 said:


> Better to maintain a healthy well balanced environment than worry about tweaking the spectrum.


Hi @oreo57 

I'm not questioning for one moment the need to maintain a healthy aquarium environment - that is a given. But that alone, in my experience, will not necessarily prevent problems with cyano outbreaks. Tweaking the spectrum on its own will not keep cyano at bay.

JPC


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## jaypeecee (9 Feb 2021)

dw1305 said:


> I still can't see where there is enough difference between the two light absorption curves?


Hi Darrel,

To which two absorption curves are you referring?

JPC


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## JoshP12 (10 Feb 2021)

Hi all,

Just want to share a story about spectrum ... it is important to consider it. 

Consider the following scenario:
1) Turned up my CO2
2) Noticed I overshot it and fish were struggling
3) Shifted my spectrum towards more Red and warm white:
              Sacrificed Cool white spectrum for Warm white (oranges and yellow and green) and Red.
               Got rid of about 10 % of cool white and it equated to about 15% Dark Red (660nm) more AND maybe about 7% of warm white (the numbers will not add up properly -- I just redistributed it)   ... fish began to recover near end of photoperiod (could be lots of reasons why so don't draw crazy conclusions)
4) The next day - no gasping.

It isn't the first time that I tweaked light to help dial in CO2 and it isn't the first time I tweaked spectrum instead of tweaking that CO2 dial.

Just an experience in how I help myself set CO2.

Josh


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## ceg4048 (10 Feb 2021)

jaypeecee said:


> You may be correct but what (scientific) evidence do you have to back up your statement? I'd also like to pick up on your word 'triggered'. I don't see it as necessarily 'triggered'. Isn't it a case of orange light at 625nm having the potential to 'feed' cyanobacteria with light of the very wavelength that it is well-equipped to utilize? Red light at around 660nm is needed by plants as it corresponds to one of the absorption/action peaks of chlorophyll a - as I'm sure you are very much aware. So, red light is here to stay. The other chlorophyll a peak is at 430nm give or take a gnat's whisker. This is at the blue end of the spectrum and, according to Dr Bruce Bugbee*, is very much needed but, in his words, 'shrinks plants'.


As Darrel alluded to, and as mentioned in oreo57's post, the problem in interpreting and applying this data is one of magnitude. It's all very easy to get wrapped tightly around the axel about this nanometer, or that response curve. How much does all of that translate to what is in our tank in comparison to the contribution of the wide range of other factors such as CO2, nutrition, genetics, light intensity, flow distribution and so forth?

The best solution is to test this for your self, in real tanks. You first need to have control. Do you have enough control of the tank to be able to detect the differences in growth and health and to be able to attribute those differences to blue alone? Doubtful.

Years ago we played with different bulb types to determine if we could at least subjectively determine a performance differences between various colored bulbs. There was no way we were going to be able isolate specific frequencies using T5s (perhaps it's less of a problem now with LED) so we just used bulbs based on supposed color temperatures and had a look at their published spectral curves. 

My blue containing bulb choice was Osram 880. A supposed 8000K bulb. No shrinkage was detected.







In comparison, these bulbs are Osram 840, a supposed 4000K bulb with lots of orange/yellow. No problems either, just lots of exaggerated orange/yellow.




Many others have done similar, searching for the holy grail of spectrum and none of us could determine, subjectively, which bulb color performed best. There were just too many variables. Could it have been done more scientifically? Sure, we could have isolated individual stems in a petrie dish and measured the dry weight after X weeks, but to what end? If the tank conditions were good there was no real overall difference in performance. If problems developed in the tank, such as flow issues or CO2 issues, the symptoms were similar across bulb types. You simply cannot separate effects of wavelength from these other factors. Again, these were not just isolated tests. Various lamp types and bulb combinations have been used over the years and no one could say unequivocally that this wavelength is superior to that other wavelength. It's simply a non-issue in our tanks, regardless of the results of that experiment, because the other factors have effects orders of magnitude above the effects of wavelength.


Cheers,


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## dw1305 (10 Feb 2021)

Hi all,


jaypeecee said:


> To which two absorption curves are you referring?


These, from the paper you referenced <"Blue light reduces.....">:





_Light absorption spectra of the cyanobacterium Synechocystis sp. PCC 6803 (black line) and the green alga C. sorokiniana 211-8K (grey line) acclimated to 35 µmol photons m−2 s−1 white light._

cheers Darrel


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## jaypeecee (10 Feb 2021)

Hi @JoshP12 @ceg4048 @dw1305 @oreo57 

Many thanks for all your feedback. I plan to do some experiments for myself when time permits. If, and when, time does become available, I'll report back.

JPC


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## erwin123 (10 Mar 2022)

Covering crops in red plastic can boost yields up to 37 per cent
					

A simple, cheap technology could help to boost food production and possibly allow crops to be grown in different places in order to cut down on food miles




					www.newscientist.com
				






> To address these issues, Alexander Soeriyadi and Alexander Falber at the University of New South Wales in Sydney, Australia, developed *a material called LLEAF that passively converts some of the green wavelengths in sunlight* – which are less important for plant growth – to red ones.
> In greenhouse trials, the researchers found that the material increased plant yields by an astonishing amount for various crops, including 37 per cent for pak choi. The material is now being tested in bigger, independent trials run by Western Sydney University and the New South Wales government’s Department of Primary Industries.
> 
> David Tissue at Western Sydney University and his colleagues recently completed a trial of the material. They installed it over a greenhouse to cover a 200-square-metre plot of lettuces next to an identical plot of lettuces that wasn’t covered by LLEAF. The yield of cos lettuce, also known as romaine, rose by 14 per cent under the material, while that of butterhead lettuce increased by 27 per cent.
> ...



Found this interesting, but rather than create a new thread, I thought it best to add this to the most recent light spectrum thread....


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## oreo57 (10 Mar 2022)

erwin123 said:


> Covering crops in red plastic can boost yields up to 37 per cent
> 
> 
> A simple, cheap technology could help to boost food production and possibly allow crops to be grown in different places in order to cut down on food miles
> ...




Article being behind a paywall makes it difficult to make any other observations regarding it.


> although more research is needed to see if it affects the flavour and nutrition of plants.


Actually important for crop plants.. High intensity or high blue content generally favors flavor and nutrition.
For planted tanks.. not an issue really except for possibly color..

Found this.. Interesting.. seems they are implying using green photons and re-emitting them as red??
As in "flourescence"?
That is a bit cool.
If it's JUST a filter it would decrease PAR
needs clarification..Too much market-speek.


> The films are made from special dyes that absorb and diffuse photons from the green spectrum of light, and emit it again as red light to increase plant photosynthesis.
> They reduce the amount of light which the plants can’t use, and the diffusion of the light they can is done so more evenly, and in a way as to reduce shadows.











						Covering Crops in Red Plastic Can Boost Yields Up to 37 Percent
					

An Australian ag-startup is discovering that red films atop existing greenhouses can produce more light plants need to photosynthesize.




					www.goodnewsnetwork.org
				





> LLEAF 620 is a low-red spectrum color to boost photosynthesis and increase production in most plants, while for aquatic plants, LLEAF 590 is the best choice for applications where light penetration through water for increased growth rate is required.


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## oreo57 (10 Mar 2022)

OK that parts solved.









						Covering crops with red plastic can increase yields by 37 percent - Techzle
					

Image: Pixabay/Geoluro11 A simple, inexpensive trick can boost food production and even make it possible to grow crops in places where they normally don’t grow. Growers can increase the yield of their crops by covering them with a plastic that increases the amount of red light on the plants...




					techzle.com
				





> It is a transparent plastic with a fluorescent dye that absorbs green wavelengths and gives it back in the form of red.  It can be hung over existing greenhouses.  As a result, the light inside the greenhouse turns a soft pink.  ‘It’s quite beautiful,’ says Soeriyadi.


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## dw1305 (11 Mar 2022)

Hi all,


oreo57 said:


> If it's JUST a filter it would decrease PAR
> needs clarification.


That was what I was thinking.  Sun-light is incredibly bright, so even with the inevitable loss from the conversion process it might still offer advantages. 

<"Horticultural grow-lights arrays"> are still often "narrow spectrum", so really  just red and blue LEDS.





cheers Darrel


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## erwin123 (11 Mar 2022)

Technical — LLEAF
					






					www.lleafgrow.com
				




This the interesting part though based on the chart, the conversion efficiency is quite low - a significant drop in greens and even blues, and only a slight rise in reds....  nevertheless, it seems that certain crops respond to it. Its being tested by a Aussie Govt agency so it seems legit: Smart Glass and LLEAF: novel spectra-shifting tech to boost energy-efficiency, crop growth and yield under cover


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## oreo57 (11 Mar 2022)

erwin123 said:


> Technical — LLEAF
> 
> 
> 
> ...



Chart is relative.. As the blue peak is replaced by red the entire rest of the spectrum is pushed down proportionally.
Not sure one can really say that without a par measurement. May hold, may not. 

They should present "before and after" PPFD measurments.
The seem to acknowledge PPFD losses though..


> However, *as it changes light intensity *and spectral quality.......


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