# The RED/Blue ratio



## Greystoke (Jul 24, 2010)

I’ve been looking for a simple indication that will give me a light source potential to support plant growth.

I know that RED (600-700nm) and BLUE (400-500nm) light are the most important sectors for plant growth of the light spectrum, and the *ratio* between the two would be an important indicator.
I have always thought that the solar R/B ratio (≈ 1.3) would be a good point of reference, after all, plants evolved under sunlight for millions of years, but recently I paid attention to what is known to be the *Photosynthetic Usable Radiation (PUR)*, i.e. : the light that supports the photosynthesis process in plants.








If you can measure the area underneath the curve (_by integration_) between 400 and 500nm and also between 600 and 700nm, you will get a measure of the amount of BLUE and RED covered in the graph.
In doing so, and dividing the values into each other, we find a *RED/BLUE ratio of ≈ 0.5*. In other words: The photosynthesis process requires about twice as much BLUE compared to RED, when measured in PPF (PAR/m²).

I find that level very surprising when compared to the solar R/B ratio of 1.3. I did not expect plants to be significantly different.

Fortunately, I was not the only one.

December 2008, Tom Barr said:


> _The red/blue % is interesting and you'd suspect a large % of red and a small amount of Blue would yield the best PUR.
> 
> Regards,
> Tom Barr_


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## FlyingHellFish (Nov 5, 2011)

Whoa, that is surprising. I hear people add more Red compare to Blue, but now maybe it's its other way around.

My lights allow me to up the red or blue spectrum in % so I'll try upping the blue. There wasn't a huge difference between red and blue pearling for me, I'll try to capture the video and let you guys be the judge.
I thought the lower end spectrum were more beneficial to marine tanks, compare to freshwater.


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## jeffkrol (Jun 5, 2013)

Greystoke said:


> I’ve been looking for a simple indication that will give me a light source potential to support plant growth.
> 
> I know that RED (600-700nm) and BLUE (400-500nm) light are the most important sectors for plant growth of the light spectrum, and the *ratio* between the two would be an important indicator.
> I have always thought that the solar R/B ratio (≈ 1.3) would be a good point of reference, after all, plants evolved under sunlight for millions of years, but recently I paid attention to what is known to be the *Photosynthetic Usable Radiation (PUR)*, i.e. : the light that supports the photosynthesis process in plants.
> ...


Photosynthesis efficiency is not the complete story..

AS to the "best" ratios of b/r I believe that is still open to interpretation:


> They recommend a mixture of blue and red LEDs to enhance lettuce-crop quality and yield in closed-type plant-production systems; the best results for lettuce arose from the blue:red ratios 35:65, 47:53, and 59:41.


Sorry, without paying I can't find anything more than an abstract..
http://www.laserfocusworld.com/arti...wth-and-antioxidant-compounds-in-lettuce.html

or:


> However, 0 B (100% red LED) induced a significantly higher leaf shape index, which represents elongated leaf shape, compared with the other treatments. Increasing blue LED levels negatively affected lettuce growth. Most growth characteristics (such as the fresh and dry weights of shoots and leaf area) were highest under 0 B for both cultivars compared with all other LED treatments. For red and green leaf lettuce cultivar plants, shoot fresh weight under 0 B was 4.3 and 4.1 times higher compared with that under 59 B after 4 weeks of LED treatment, respectively. In contrast, the accumulation of chlorophyll, phenolics (including flavonoids), and antioxidants in both red and green leaf lettuce showed an opposite trend compared with that observed for growth. The SPAD value (chlorophyll content), total phenolic concentration, total flavonoid concentration, and antioxidant capacity of lettuces grown under high ratios of blue LED (such as 59 B, 47 B, and 35 B) were significantly higher compared with 0 B or control conditions.


http://hortsci.ashspublications.org/content/48/8/988.abstract

It is always "complicated"......... 



> For red and green leaf lettuce cultivar plants, shoot fresh weight under 0 B was 4.3 and 4.1 times higher compared with that under 59 B after 4 weeks of LED treatment, respectively. In contrast, the accumulation of chlorophyll, phenolics (including flavonoids), and antioxidants in both red and green leaf lettuce showed an opposite trend compared with that observed for growth.


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## jeffkrol (Jun 5, 2013)

FlyingHellFish said:


> Whoa, that is surprising. I hear people add more Red compare to Blue, but now maybe it's its other way around.
> 
> My lights allow me to up the red or blue spectrum in % so I'll try upping the blue. There wasn't a huge difference between red and blue pearling for me, I'll try to capture the video and let you guys be the judge.
> I thought the lower end spectrum were more beneficial to marine tanks, compare to freshwater.


That is mostly due to 1)what people think a reef looks like 30M underwater
2)Slight differences in coral response to light attenuation.. though it takes a lot of depth (relatively speaking to freshwater rivers/streams/lakes) to absorb all light but blue/green..


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## FlyingHellFish (Nov 5, 2011)

Any idea on how to test this out? I'm not sure if a conclusion can be made solely on the level of pearling so I'm contradicting myself here. 

What I do know is, I have a light that controls both high end Red and low end Blue. Both lights are independent of each other with timers. 

If anyone has a good idea to test this theory out, I offer my tank as a test subject.

Either that, or someone can give an insight as to which is "better". Surely there was a time when someone blasted Red compare to Blue.


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## jeffkrol (Jun 5, 2013)

FlyingHellFish said:


> Any idea on how to test this out? I'm not sure if a conclusion can be made solely on the level of pearling so I'm contradicting myself here.
> 
> What I do know is, I have a light that controls both high end Red and low end Blue. Both lights are independent of each other with timers.
> 
> ...


I've blasted "blue".. actinic/10000k and ended up w/ VERY compact water wysteria.. i.e practically zero internode elongation.. 

As to blasting red..


> Most growth characteristics (such as the fresh and dry weights of shoots and leaf area) were highest under 0 B for both cultivars


granted this was lettuce..but I'd be surprised if this was any different for most plants..though it would probably be for some......

Short of death, what appears "healthier" is too subjective.. i.e tall vs short is not a matter of health in general.. 

Unless you are growing plants commercially (or have a need for a specific characteristic i.e more fruit, compact plants) I doubt that any reasonable ratios would be wrong...... 



> Stem elongation of the lettuce seedlings was accelerated by red/blue PPFD ratios of 54/6 and 48/12, and whole plant dry weight was a maximum at a red/blue PPFD ratio of 48/12. Stem length was significantly decreased with an increase in the blue PPFD. Although growth of whole plants was accelerated by a red/blue PPFD ratio of 64/16, maximum values of root and stem dry weight occurred at red/blue PPFD ratios of 56/24 and 72/8, respectively.


IF you relate "bio-accumulation" to health.. The more red the better.........


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## FlyingHellFish (Nov 5, 2011)

Ooh snap! Really? I been trying to figure out what determine internode length for a while now. What were you fertilizing? Is lower blue light the size, and higher red the colour/appearance?


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## jeffkrol (Jun 5, 2013)

FlyingHellFish said:


> Ooh snap! Really? I been trying to figure out what determine internode length for a while now. What were you fertilizing?


nothing at the time... besides fish waste..


FlyingHellFish said:


> Is lower blue light the size, and higher red the colour/appearance?


Not sure I'd be comfortable saying that. High blue:red ratio will "stunt" elongation.. According to the study above.. high red: blue will generally increase biomass.. How that translates is a bit questionable.. 

As to color.. well I'm not convinced it is totally light dependent though in low light obviously most plants won't waste their "time"  producing accessory pigments, or conversely produce more chlorophyll masking the pigments.. 

My color effects are indeterminate at this point .. My Hygrophyla c. used to look like this (borrowed image) w "blushes" of pink red. currently it is dark green and stretching..:


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## FlyingHellFish (Nov 5, 2011)

^ Beautiful plant! Looks healthy and I like the red hue.

I tried altering the size and appearance of plants by changing the fertz, it did not go too well. Beside getting uniform growth, I think the majority of the changes were deficiencies rather than controlled growth.


I got some of your results, but very sad looking plants rather than healthy ones. An example would be a decrease between the internod, but with a pale wash out colour. I also managed to get larger leafs but with longer internod. Not to mention, I some how to a ton of auxiliary buds to form on rotala round.

Anyways, you got any more examples of blue vs red spectrum?


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## jeffkrol (Jun 5, 2013)

FlyingHellFish said:


> ^ Beautiful plant! Looks healthy and I like the red hue.
> 
> Anyways, you got any more examples of blue vs red spectrum?


No, never photographed the "dr Seuss" Hydro'ss .. 

A bit of a "sort of" difference.. I switched my 3500K white to 6500k..so in a sense I shifted from red to blue.. 
just as a comparison.. here is the tank last July:










This week:









This is deceiving since the compact hydro has lost most of the lower leaves recently.. but I have a smaller one in front.. trickery.. foxtail has mostly all died, I believe it was killed during my last hair algea outbreak.. It was covered w/ it as was most of the moss, which I've weeded out.. the plant in the right corner is fine but not growing.. shrinking actually but the reason is a mystery to me..
Anyway my new design includes some 3500K's.. It may be completely unrelated but I believe they are better than 6500k's..no scientific proof of this of course..









Oh in case you haven't noticed it wasn't designed to be aesthetically pleasing.. so to speak..This is my first attempt at reentering the "sport"..... 
My ones..still late July









I still feel I had a lot more "color" in the plants using the 3500k's..........


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## jeffkrol (Jun 5, 2013)

Chlorophyll absortion graphs don't always translate to actual use:










http://www.ncbi.nlm.nih.gov/pmc/articles/PMC396523/



> An absorption
> spectrum defines the wavelengths that are absorbed. An action spectrum defines
> the wavelengths that are most effective for photosynthesis. In other words, it is the
> portion of the spectrum that does the work. This is what is most important in plant
> ...


http://www.heliospectra.com/sites/w...ents/what_light_do_plants_need_2012-10-05.pdf

"poof"................


> Indeed, on an absorbed quantum basis, photosynthetic efficiency or quantum yield for green light
> is similar to that of red light, and greater than that of blue light
> in the deeper layers
> of a leaf (Terashima et al. 2009).


What I have read it this green light effect is really only valid on "high light" environments.. Also I doubt if green light efficiency is really as important w/ aquatic adapted plants.. since they are "generally" thinner and possess little in the way of barriers i.e thick waxy cutin layers.. not positive of this, but if conifers w/ their thick needles are the type of plants that exhibit the "green effect" most.. well I'll just call that circumstantial evidence..

ONE interesting thing in that "paper"... It may hve some application to aquariums...


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## plantbrain (Dec 15, 2003)

Other pigments change things a fair amount for growth and squeezing every little last bit out does not always translate into a better bulb. 

It has to LOOK GOOD and it has to do a NICE JOB with growth. 
Aquatic plants have very different issues with respect to internodal distances that have nothing to do with light.

CO2 and other stress such as low O2 and other gas exchange play a pronounced role. Food response, Jackson et al, Rice, and other google scholar search terms will help.


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## jeffkrol (Jun 5, 2013)

plantbrain said:


> It has to LOOK GOOD and it has to do a NICE JOB with growth.


That I thought was a given.. 



plantbrain said:


> CO2 and other stress such as low O2 and other gas exchange play a pronounced role. Food response, Jackson et al, Rice, and other google scholar search terms will help.


You can do better than that.. Why not include a "Smith" while your at it......


BTW: This Jackson???



> Genes for enzymes involved in several steps of the GA biosynthetic pathway have now been cloned from various different species and the expression of many of these genes is regulated by light ......
> Red light did not induce the expression of either of two GA 20-oxidases from lettuce, and with one of the genes (Ls20ox2) it was found that red light reduced its expression suggesting that Pfr may inhibit expression
> of this GA 20-oxidase (Toyomasu et al., 1998).
> However, red light was found to induce the expression of a GA 20-oxidase in pea (Ait-Ali et al., 1999). GA 20-oxidase is thought to be a key regulatory enzyme in the GA biosynthetic pathway, its expression is subject to feedback inhibition by GAs further down the pathway, suggesting that GA biosynthesis has an auto-regulatory component (Hedden and Croker, 1992; Phillips et al., 1995).
> ...


http://digital.csic.es/bitstream/10261/26323/1/Jackson_Stephen_et_al.pdf

I don't think I ever said it wasn't complicated......


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## Greystoke (Jul 24, 2010)

jeffkrol said:


> I don't think I ever said it wasn't complicated......


I wouldn't have believed you anyway . . .:biggrin:

Thank you very much for all this information Jeff. It blew away a lot of misconceptions. I am not botanically educated. I am a mathematician with a chemical background (_both very dated_) 

So I have a few questions








:

1. Is it correct that each plant species requires its own specific spectral composition?

2. If you could ensure that the light spectrum addresses ALL the photosynthetic needs of the plant, doesn't that guarantee an ideal growth pattern? (_Personally, I think it should, but perhaps I'm missing a few more points_)

3. Conversely, if the spectrum does NOT meet ALL the photosynthetic requirements of the plant, could that be construed as a spectral deficiency which - in turn - could cause an altered growth pattern?


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## JJVanier (Feb 4, 2014)

This is the only thing I can add to this discussion:

"Damn nature, you scary!.......................complicated"


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## blinky2088 (Oct 16, 2006)

Interesting. 

I have been following these grow lights red/blue since they first hit the market about 5 years ago, based on NASA research and growing food in space etc..and there are alot of products on the market right now.

I am in the process of getting 2 x 1 meter strips of the 660nm red and blue at 5 red to 1 blue ratio with dimmer switch. Each meter strip uses about 14.5 w per meter smd 5050, There are 60 bulbs per meter and rated at .25 Watt per bulb to supplement my t5ho x6 over a 75Gallon (4ft). If all goes well (Growth and Looks) I plan on only using 4 x t5ho with these strips. They also come in ratios of 8 red to 1 blue and other configurations. I suppose you can use a whole red strip and whole blue strip on seperate dimmers and reduce the amount of light on each strip seperately. Increasing intensity on reds over blues or vice versa.

There are other strips 5630smd brighter than the 5050 about 28Watts per meter or .5 Watt bulbs but the red/blue mix isnt there yet or not in the 660nm wavelength. I prefer the look of the 660nm over the 640/630nm and not 100% sure if growth is particulary better in this wavelength

It is my understanding that red is a harder wavelength to get to the bottom of the aquarium (than blue) and maybe why the red ratio is higher, whether the plants need red at deeper depths I dont know.


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## Greystoke (Jul 24, 2010)

blinky2088 said:


> It is my understanding that red is a harder wavelength to get to the bottom of the aquarium (than blue) and maybe why the red ratio is higher, whether the plants need red at deeper depths I dont know.


That is correct, but at the ruling depths of fish tanks (12" - 18") it won't make a big difference.

I would appreciate it if you could give me luminous information of the 5050 reds and blues.
I know that reds are far more efficient than blues up to a factor of 2X. It can skew these ratios badly.
What made you decide to go for these strips?


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## jeffkrol (Jun 5, 2013)

Greystoke said:


> I wouldn't have believed you anyway . . .:biggrin:
> 
> Thank you very much for all this information Jeff. It blew away a lot of misconceptions. I am not botanically educated. I am a mathematician with a chemical background (_both very dated_)
> 
> ...





Greystoke said:


> 1. Is it correct that each plant species requires its own specific spectral composition?


for most the similarities would outweigh the differences. 



Greystoke said:


> 2. If you could ensure that the light spectrum addresses ALL the photosynthetic needs of the plant, doesn't that guarantee an ideal growth pattern? (_Personally, I think it should, but perhaps I'm missing a few more points_)


Yes I assume so.. In these discussions there are 2 things.. Ideal quality and ideal quantity..
Targeting spectrums has more to do w/ "best quality" and lowest price/energy/flexibility.

BEST quality would probably 1000W HPS's or any full spectrum bulb (not phosphor driven) over your tanks...... but it boils down to expense and practicality.....

I don't like LED just because you can design very effective targeted PAR lamps but because of cost/ flexablility/ ease of use and repair/ ect.. 






Greystoke said:


> 3. Conversely, if the spectrum does NOT meet ALL the photosynthetic requirements of the plant, could that be construed as a spectral deficiency which - in turn - could cause an altered growth pattern?


The studies I read show w/ just "red" leaf shape is altered.. w/ blue internode length is altered.. I've proved that one to myself.. 

Obviously that isn't the only thing.. Nutrients/env. stress/predation all play a factor in developed response... But light is important.. The simple example of "water wysteria" and the 2 leaf forms.. highly dependent on light quality/quantity..

conversly there are plants whos morphology changes based on being submerged or aerial... can't pin that on light per se...

Looking at most scientific literature in any field.. there are more unknowns than knowns........ 

I'm brushing off my Botany degree daily..... a lot has changed, a lot stayed the same..... 

in a sense my "philosophy" boils down to all chemical reactions need an energy gradient. Light provides that for plants.. Food provides that for us. So all reactions boil down to light for plants.. Simplistic but functional..  

Getting into which bandwidth pushes w/ reaction pathway on which receptor gets pretty complicated esp. when you chain them all together..adding shifting reaction equilibra.....

Making cheap, efficient, highly functional lighting that looks good is a goal not increasing leaf area by .25mm.. for most.... 

but understanding the generalities that go into it is important..

fun example of Pf and Pfr species specific response..
http://faculty.caes.uga.edu/pthomas/hort4050.web/Hort4050web/Phytochrome lecture.pdf


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## blinky2088 (Oct 16, 2006)

I decided to use the 5red:1blue ratio as it was the closest to 1:1 ratio I could find. Maybe next time I will use a full strip red and a full strip blue. There are also 7:1, 8:1 and 10:1 using teh same 120 Degree bulb smd5050 and peak at 660nm.

5050smd led claims 4 lumen per led and there are 60 led in a meter so I will be using 2 x 240 about 480 Lumens on my 75 Gallon, in addition to my T5Ho's. Par data I do not know and cannot confirm the lumens its more an experiment. 

I wouldnt want the red/blue mix to be overpowering to look at. I have purchased older model 55w square panel blue red fixtures before and they were very bright and difficult to look at without goinf into a seizure, ( In ever used it over an aquarium always wanted to but it was too wide and I could not keep t5ho working at the same time. And I figure alot of the aquarium LED companies are putting out about 50 Watt fixtures just more in the full spectrum with different mixture of bulbs, where I should already achieve full spectrum from the T5HO middays etc.. and these led strips will be close to 30 Watts.

I would prefer the mixture of red/blue to be closer to 1:1 because I dont want a fish to swim by and look very red one minute then maybe a dull red/blue when it swam past the blue led. (As a side note this was the feeling I got when led lcd tv's first came out...I dont think they used diffusers etc....prices were extremely high, but if you looked closely you could tell where the led were placed....Not sure if that still occurs or not but almost gave the screen a bumpy/wavy appearance)

I am still not convinced that Leds only are the right answer for me but want to try them out as a supplement to my tanks for additional growth and looks.


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## plantbrain (Dec 15, 2003)

Aquatic plants are not the same when it comes to internodal length response to light as are terrestrial plants. They have many other aspects, such as gas exchange, which dictates the internodal distances and escape of the low O2 and poor CO2 environment. 

Jackson et all provides a good model for how the plant responses to flooding(non aquatic/flood tolerant plants die). Most all of the plants we keep are amphibious. 

http://aob.oxfordjournals.org/content/101/2/229.full

See figure 4.

Voesenek also:

http://www.uu.nl/faculty/science/EN...blications/Documents/2009/Colmer FPP 2009.pdf


Having used a variety of bulbs over the years, I've seen virtually no comparative correlation between such claims on light. Giesemann made some observations with aquatic plants that do mirror my observations regarding color.

I use 6 reddish bulbs to 2 blue bulbs, this yields a nice coloration. Many other issues factor into compact growth other than the spectra.
Without accounting for those factors, you cannot say really much. 

Things as simple as trimming, and pruning methods can have large changes. Limiting ferts can lead to this also. You need to have some sort of control, if you lack the control to begin with, well, you cannot say much either way. Maybe there is something to it, but I've yet to see evidence that I would agree with.


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## jeffkrol (Jun 5, 2013)

Much of this is not based on true aquatics...........


> In Ranunculus repens (Ridge, 1987), Rumex palustris (Voesenek et al., 1993), Ranunculus pygmaeus (Horton, 1992) and many other wetland species, the fast extension rates of submerged plants are sustained even after re-emergence. This can propel the lamina well above water level (Fig. 2).


most aquarium plants don't have a "emergent" period.. Not sure how you would "trap" Ethylene.. or change it's ratio for that matter...

IF you care to repeat my "experiment" on a small level.. take one:


> Emitted Color: 3 chips 10000-12000K + 6 chips 450-460nm Royal Blue
> 
> DC Forward Voltage (VF) : 9-12V DC
> 
> 10W Watt Actinic Royal Blue Hybrid 45Mil Led


Some water wysteria.. run it for a month.. See what it looks like..simple cheap experiment.

Light levels vs CO2 a little interesting paper..
http://www.bio-web.dk/ole_pedersen/pdf/PlantedAquaria_2001_2_22.pdf


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## jeffkrol (Jun 5, 2013)

food for thought.. Oddly found red to inhibit stem elongation in low light conditions... 
http://www.apms.org/japm/vol15/v15p29.pdf

Interesting part..
"They (see txt) reported that both aquatic species elongated rapidly under red light.........."


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## OVT (Nov 29, 2011)

This is my first subscribed to thread, ever.

v3


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## Greystoke (Jul 24, 2010)

I must pay attention here, coz I could so easily lose my way. 

Another aspect pointed out to me by a friend (_Tyrone Genade_) is that the absorption spectra of the two chlorophylls are narrow and have different centers. This means that, you may well have a lot of Blue and Red light shining on your plants, but if they don’t cover the effective bandwidth of the absorption peaks, those lights could serve little purpose.








Compared to some typical LED spectra:








There is definitely a mismatch here, which may well explain some unsuccessful attempts in the past.
However, there are some small overlaps, and perhaps it would be a good idea to find out how much.


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## jeffkrol (Jun 5, 2013)

Greystoke said:


> I must pay attention here


I'm still trying to find an absorption chart I trust.. I shoudn't rely on visual interpretation but I'm inherently lazy... 

I've noticed the carotenoid peaks are all over the "charts" so to speak..










Second peak under 500, over 500 on 500... yeesh..



> For example, lutein has its maximum absorption at 450 nm, cryptoxanthin at 453 nm, and zeaxanthin at 454 nm.


sorry for the diversion...

Oh as to red.. This is why I don't favor normal red LED's.. Keep in mind that the actual "normal" red led can vary a lot too.. If someone had red w/ a low "orange-ish" peak it would be arguably less effective than a red w/ a peak higher.. commercial variance seems to be rather high, or so I read..


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## Greystoke (Jul 24, 2010)

Hi guys,
I’m not through on this subject yet. I’m going to pursue it a bit further using the info obtained thanks to you all
For the moment I worked on the problem of spectral mismatches between plants and light sources:







This picture shows the mismatch between chlorophyll-a and the red and blue light sources.
As shown, the chlorophyll only captures ≈10% of the blue light and ≈25% of the red light








This picture shows a much better match for chlorophyll-b and the same light sources.
The chlorophyll captures 80% of the blue light, and 90% of the red.

Of course, this is the result using the available information. The chlorophyll spectra are accurate (I think), but I understand that the LEDs may be subject to production variables that move the central peaks around.
That could spell disaster for chlorophyll-a.

We need to find more info on this.


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## jeffkrol (Jun 5, 2013)

> Figure 1.8 Upper curves: Diethylether solutions of chlorophyll a (Chl a, solid line) and chlorophyll b (Chl b, dotted line) show distinct absorption peaks in
> blue and in red regions of the visible spectrum (redrawn from Zscheile and Comar’s (1941) original data). Fluorescence emission spectra (inset, redrawn from Lichtenthaler 1986) show peaks only in red, and at wavelengths characteristically longer than corresponding absorption peaks, namely 648 cf. 642 nm for Chl b, and 668 cf. 662 nm for Chl a. Lower curves: In situ absorption spectra (eluted from gel slices) for pigment-protein complexes corresponding to photosystem II reaction centre (PSII RC) and light-harvesting chlorophyll (a,b)-protein complexes (LHC). A secondary peak at 472 nm and a shoulder at 653 nm indicate contributions from Chl b to these broadened absorption spectra which have been normalised to 10 µM Chl solutions in a 1 cm path length cuvette. (Based on from Evans and Anderson 1987)



Food for thought............


> Subtle alterations in the molecular architecture of chlorophyll molecules according to the particular protein to which they bind in either light-harvesting or energy-processing centres are responsible for these shifts in absorption peaks, and for a general broadening of absorption spectra (compare lower and upper curves in Figure 1.8). Such effects are further accentuated within intact leaves by accessory pigments and greatly lengthened absorption pathways resulting in about 85% of visible wavelengths being absorbed (Figure 1.9).














> Any absorbed quanta at wavelengths below 680 nm can drive one electron through either reaction centre. Maximum quantum yield (Figure 1.9) occurs when both reaction centres absorb equal numbers of such quanta.


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## plantbrain (Dec 15, 2003)

jeffkrol said:


> Much of this is not based on true aquatics...........
> 
> 
> most aquarium plants don't have a "emergent" period.. Not sure how you would "trap" Ethylene.. or change it's ratio for that matter...



Virtually 99.5% of the plants we do grow are amphibious and they need some mechanism that tells them they are submersed or emergent. These are aquatic plants by the definition of wetland soils. They can survive submersion and flooded soils, most plants cannot, which makes them a far better analog than other options, which we do not have available

Ethylene is easy to reduce the diffusion like O2 or CO2 etc in water, the diffusion rates slow down 10,000X vs air. Water can be degassed to remove it faster(high current) vs still water or add a oily cap to the water surface. There are a number of simple treatments hobbyist can do. Emergent growth can be done pretty easily. We can seal gas exchange in emergent tanks pretty good to mimic submersed gas diffusion. Tight fitting lid. Many folks do this with poor results using DMS methods. 


This is a good reference for what I've observed and argued for:
http://www.apms.org/japm/vol15/v15p29.pdf

Suggest that red light is better. Not blue. Particularly at lower light intensities which Bowes et al above used and what most hobbyists use. CO2 also plays a huge role in aquatic plant growth and light use. Few studies add CO2 and then look at the light spectra. They did add some carbonate as both plants can use this indirectly as a carbon source. 

These are all nice and such, but little specific research is going to answer the questions specific to the hobbyists, what makes plants grow more stout and bushy and what produces nice red colors? 

Well, you can simply try various bulbs and see what happens.
I did. Seems to work better than most methods I've heard folks discuss on line for the last 2 decades. Then you can look at what those bulbs do/did as far as the spectrum. Now it's specific to the aquatic plants we grow and care about and you have a comparative gauge. 

I'm not going to use and set up a LED system and a tank just to see this effect, I will/have change/d out things in my 120 or 180 Gallon and switch bulbs around. This way I have a lot more options and plants to see if things are doing well or not, and I also know the tanks are doing well in terms of the other parameters, so they offer a good nutrient, good filtration/general care routine, good CO2 etc. I'm not a big fan of LED's, I've seen some decent tanks recently though.

Some plants might have some impact with certain treatments, others might not, if you do 20 species, then you can say a lot more.

IME, poor CO2 leads to leggy growth, not the lighting so much.
Since all that light energy is used for Carbon reduction...if that's limited, then the light is not going to matter nearly as much, you have poor light use efficiency. Little CO2, low O2, increased levels of Ethylene. and poor plant growth. If you have non limiting CO2/nutrients, good care, good nice examples of plant groups, then you have a less less dependencies. 

Without a holistic view of plant growth/practical planted aquariums and where this energy goes and the downstream effects, I think we miss a lot of the big picture here. 



> I'm still trying to find an absorption chart I trust


I agree 100%.


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## Greystoke (Jul 24, 2010)

This is the honest ME :angel::

I’ve been in this type of light research for close to 10 years.
I started with fluorescent lights. Hunting down their spectra, from which I managed to extract interesting information such as: Kelvin rating, Red/Blue content, PAR output, etc.

I also made a list of the most successful fluorescent lights that stimulate the growth of aquatic plants, such as:
Sylvania Gro-Lux,
Giesemann Powerchrome,
GE 9325K,
Arcadia Plant Pro,
etc, etc.

But other than finding that most of them belong to the “Cool White” or “Day light” sectors, I have never been able to determine (from their spectral characteristics) why these bulbs are known to be the “champions” of the hobby, whereas other (cheaper) bulbs with similar characteristics are not so popular.
Today we have a situation where someone could draw a likely bulb from the shelves and ask if it would be OK to grow plants. Probably the most frequently asked question on this forum, and the answer (?) = “definitely maybe”.

And LEDS (?) . . . well never mind, but . . .
I am determined to get to the bottom of it.

So far I suspected that some of the light sources (fluorescent AND LEDs) do not fully match the absorption spectra of our plants basically because these lights tend to generate distinct beams of narrow bandwidth (≈20nm) which may or may not match (“near missing”) the demand peak.









Jeff shows that plants have the surprising ability to shift their absorption peaks. However, from the example it doesn’t seem enough to bridge the differences between the peaks of the various light sources that are available, which needs to be at least 20nm .


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## ua hua (Oct 30, 2009)

Very interesting read guys. Thanks for all the info and time put into this. I have recently tried a few different combos of lights and now have settled on 3 reds and 3 blues. I was running more blues in the past but decided to try a little more red and see how it works. I may even remove 1 of the Geismann midday and replace with another red bulb. It does really bring out the red in the plants but haven't seen any difference in growth.


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## OVT (Nov 29, 2011)

plantbrain said:


> I think we miss a lot of the big picture here.


Unfortunately, my feelings exactly: trying to solve a Gaussian equation with too many unknowns or trying to approximate circumference with too few squares. My nagging question is what are we leaving behind in those "moons" by trying to approximate the continuous sun spectrum by using more and more discrete, narrow bandwidths (from tri phosphorus and now to LEDs) ? Even prior to that, we discarded anything outside of the visible spectrum, marking the leftovers as inconsequential.

Another analogy would be removing a part here, a screw there from a fine Swiss mechanical watch (without knowing or understanding it's inner workings) and checking if it still keeps time well enough.

Another one would be discarding salt from human diet, after all we consume it in trace amounts, so, it won't be missed.

By training and by nature, I question every leap from step A to step B: the solar spectrum, is it an approximation, where was it taken, what weather conditions, altitude, what instrumentation, etc etc. Is it the same in, say, Norway as in Chile? The peaks of spectral absorption in plants: what plants, growing in the exact same location where the solar spectrum was 'taken'? Then trying to derive one approximation from another approximation, what does that do to our error factor? Two standard deviation apart? Are plants just made out of chlorophyll X? Are we missing that 20 mm wide obscure spectrum that is responsible for some tiny, but vital function? And we still trying to figure out how to correctly measure PAR of the "red" spectrum.

Questions, questions ...

Plant health. Is that total weight? Nutritional value? Ability to regenerate? How can we measure something that still does not have defining criterias? Is our subjective perception of beauty (red red) has any correlation to God's/Nature's 'perfect' creation? How can we improve 'perfect'? By forcing a given plant to produce more specific pigment, how are we affecting the 'perfect' balance?

Are we subconsciously engaging in eugenics? Look at what humans did to dogs: the majority of AKC's recognized breeds did not exist 200 years ago. By molding a living thing to our needs, we also managed to increase blindness, hearing loss, respiratory problems, infertility etc occurrence in our subjects.

Circling back to OP, I leave with this question: why can I name a ton of green plants, some red, and even yellow plants but I draw a blank to name a single blue one?

If we take the premise that plants produce specific pigment as a protection mechanism against specific light spectrum to heart (stop! I have no more need for red), then maybe the answer is right in front of our noses. 

Then again, my plants seem to prefer red 

v3


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## Greystoke (Jul 24, 2010)

What I learned from solving problems in the industry is that after the first meeting of the involved there appeared to be too many issues to deal with.

The trick was to cut them down to the three most important ones and leave the rest for later.

To arrive there, we used a system called: KEPNER TREGOE. It regulated the way to get to those three, ensuring that they are indeed THE MOST IMPORTANT ISSUES.

I'm doing the same thing, except that I am (practically) my own meeting, which is a bit like playing chess against myself. :icon_lol:

The spectral mismatch is the first issue. Will it survive against peer criticism?


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## OVT (Nov 29, 2011)

Exactly, as I have very similar experiences in my industry. Given that I lack formal education in the pertinent sciences, the best I can do is to play Devil's Advocate, to provide that chess opponent, regardless of how outranked, in hopes of helping people like yourself to get better at their game. My self-interest being that the *right* 3 key areas are identified.

In my industry, I am paid to worry about the unknowns, to predict all possible dead end scenarios in order to avoid them, and, therefore, increasing the probability of a successful result. I am well aware of how negative this approach comes across in human communications and how it can be misinterpreted. That negativity is not criticism, it is yet another tool to separate chaff from the grain. Hopefully, it is taken or discarded in that context.

To add to my 'noise' above and to expand a bit on the subject of 'plant health', one fact in a related industry caught me by surprise. Beeing an outsider to the diary industry, I subconsciously assumed that production of milk by volume is what drives the financials. In fact, it is the total volume of fat delivered. Therefore, minimizing the volume of milk and maximizing the volume of fat us one of the golden grails.

Edit: if you, as the OP and one of the principals in the conversation, deem my voice more of a hindrance then a catalyst, I will revert to the role of a silent observer, with no negative connotations on my part.

v3


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## Greystoke (Jul 24, 2010)

OVT said:


> Edit: if you, as the OP and one of the principals in the conversation, deem my voice more of a hindrance then a catalyst, I will revert to the role of a silent observer, with no negative connotations on my part.
> v3


 Not a chance. I'm clutching on the straws of realism. I need them :icon_lol:


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## plantbrain (Dec 15, 2003)

Greystoke said:


> Not a chance. I'm clutching on the straws of realism. I need them :icon_lol:


And there's not a lot of them to go around either
Good post prior too.

While I have the background, I also ask what does all this really mean at the end of the day? Yes, I can and have done various test and dosing routines and spent a lot of time fiddling with ferts and what not, but a simple water change and then post dosing after manages things much easier for myself, and for most folks. 

There needs to be a practical side to all of this.

Otherwise no one will understand nor do it, that's a reality that we cannot escape. Human social issues versus biological. I do not think we need to offer a lot of techy info to sell/argue for something. A person with reasonable common sense should be able to decide on their own.

Will they make mistakes and bad assumptions? I hope so.
Otherwise they are not learning much. 


I think you make a good argument for the brands that have historically worked well within the hobby.

I've used a lot of the MH's fixtures and the T5's. LED's? A lot of variation in the following: spread, intensity, color/spectra between users world wide. there's little consistency. That lack of consistency makes the issue of lighting and replication MUCH more difficult. 

I'd hoped that using the Apogee light meters would standardize things better and they have, but things like LED's and precise what about the spectrum is helping, this is a much more difficult set of questions to answer, but we are better off today than 20 years ago. 

How much farther do we really need to go for helping folks?
This reality is something I often ask.
Do we need such data? 

How much work, effort, cost is associated with that vs say, just buying a bunch of light bulbs and trying it and seeing what you like best personally?
Aquarist A, B and C use light bulbs made buy X, Y and Z brands.

They have good colors and results, so..........

Then another aquarist comes along and has even better colors and health etc.
We have the umols/standardized intensity...........so that can be accounted for, then the rest is likely the spectrum. We never get perfection, but we do get better results and colors and have a baseline to work with.

Then go from there.
Any hobbyist can do that and it's a fairly simple easy to understand concept, and it's likely to help folks generally. We can always go back and hypothesize why those specific bulbs or combination of bulbs seem to work better.

That said, I've had FAR MORE SUCCESS using bulb combinations than a single bulb type. The T5 bulbs offer a lot more options and configurations than say a 1-2 bulb T12 fixture and with 6-8 different bulb combinations, I can certainly experiment much more with different brands.

I've spent maybe 1000-1500$ on T5 bulbs the last 2-3 years now. But I have a good handle on what works really well. This is not a cheap method, but it's one an aquarist could do. I've found more utility doing that than any discussion on spectrum. But I think light meters really helped a great deal and answered many questions. 

But once those questions were answered with intensities, now the questions lead to light efficiency and spectrum. These are much harder/more $$$ to measure and gauge.


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## plantbrain (Dec 15, 2003)

OVT said:


> Are we subconsciously engaging in eugenics?
> 
> Then again, my plants seem to prefer red
> 
> v3


Certainly many do when it comes to light in planted tanks. 
Old days, well, all we had were FL's and cool white and warm white, so 3000-4000K ranges, then 5000 daylights, then 6500 Daylights. In the mid late 1990's, 6500-Atinics, and 10,000K were the rage. Then even higher K bulbs. Then lately, red colors more. 

So Yellow/red to white, to blue, back to red.


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## jeffkrol (Jun 5, 2013)

plantbrain said:


> I've spent maybe 1000-1500$ on T5 bulbs the last 2-3 years now. But I have a good handle on what works really well. This is not a cheap method, but it's one an aquarist could do. I've found more utility doing that than any discussion on spectrum. But I think light meters really helped a great deal and answered many questions.
> 
> But once those questions were answered with intensities, now the questions lead to light efficiency and spectrum. These are much harder/more $$$ to measure and gauge.


Actually that is the strength of LED, at least DIY..
4 channels are easy and relatively cheap to build.. single LED's are also relatively cheap..so
Instead of buying the "newest" and/or "Greatest" bulb out there, a well balanced LED fixture can achieve unlimited spectrum by simple dimming.. 

Fluorescent and their mercury content are history AFAIAK.. 

That said there are even lights "better than LED" coming around the bend..

Of course an attitude like mine is less effective for the economy... 
How many "great new bulbs" turned out to not be worth the price paid..

Defining the "basics" is crucial to this success though........ 
As is defining ones own personal preference to color/reflections ect..


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## jeffkrol (Jun 5, 2013)

YEESH.. now we have to throw green into the mix (on a personal note, my next build.. "cyan" included.. )

anyways a little "something" for everyone..

Blue light produces red plants.. 


> ANTHOCYANIN ACCUMULATION
> Blue light has long been know to induce gene expression that leads to anthocyanin synthesis, and the response is mediated by cry1 ( Ahmad et al., 1995 ). The accumulation of anthocyanin
> under blue light is fl uence-rate dependent ( Lin et al., 1996 ). Blue-light-regulated anthocyanin biosynthesis is also found in many other plant species, such as lettuce, tomato, and rapeseed
> ( Giliberto et al., 2005 ; Chatterjee et al., 2006 ; Zhang and Folta, 2012 ). However, when green light is simultaneously delivered with blue light, the level of anthocyanin is lower than blue light
> ...





> Ethylene has been implicated in mediating shade avoidance responses. A low red to far-red ratio can dramatically stimulate ethylene biosynthesis in both tobacco and Arabidopsis plants
> ( Pierik et al., 2004a , 2009 ). Increased levels of gaseous ethylene promote stem and petiole elongation, but have little effect on leaf hyponastic growth. The stimulated stem and petiole
> growth by ethylene is attenuated in ethylene-insensitive tobacco plants ( Pierik et al., 2003 , 2004a ). Ethylene is also one of the
> phytohormones that mediate shade avoidance responses to low blue light. The reduction of blue light photon fl uence rate in
> ...


http://www.amjbot.org/content/100/1/70.full.pdf+html



> Plants have evolved sophisticated sensory photoreceptors, which coordinately judge the quality, quantity, direction, and duration of light, to regulate diverse
> photomorphogenic responses throughout their life cycle (Gyula et al., 2003; Sullivan and Deng, 2003; Franklin and Whitelam, 2004). These sensory photoreceptors
> have been classified broadly into three groups based on the wavelength of light they perceive. Phytochromes, which are best characterized and extensively
> studied, comprise a small family of red/far red (600–750 nm) sensing photoreceptors (Khurana et al., 1998, 2004; Quail, 2002; Chen et al., 2004).
> Cryptochromes and phototropins perceive the blue/UV-A (320–500 nm) part of the solar spectrum (Briggs and Olney, 2001; Khurana, 2001; Cashmore, 2003; Lin


http://www.amjbot.org/content/100/1/70.full.pdf+html


> Fluorescent bulbs emit three principle wavebands, approximately equal fluences of blue, red, and green light that are perceived by the human brain as white. Filtering or supplementing GL may be a useful tool to affect plant growth in general or regulate progression through key developmental stages. These concepts, as well as tests of interaction between GL and other photosensory systems, are ongoing and will determine the biologically relevant effects of GL on controlling plant development through the transition to the light environment.


http://www.plantphysiol.org/content/135/3/1407.full?sid=d07f9a97-3166-4267-96e0-f25e8458b7dd

In conclusion (well not really)


> Focused on LEDs
> Folta said all of the research being done involves the use of LED lights.
> 
> “LEDs allow us to deliver very precise amounts of specific wavelengths,” he said. “LEDs allow us to mix the light conditions precisely. We can pick and choose the light we want to use.”
> ...


http://hortamericas.blogspot.com/2013/09/using-leds-to-manipulate-plant-growth.html


Interesting study on 3 types of "white" LED's:


> Overall, the low blue light from warm white LEDs increased stem elongation and leaf expansion, whereas the high blue light from cool white LEDs resulted in more compact plants. Initial growth under cool white
> LEDs should promote the growth of short, sturdy hypocotyls. Subsequent transition to warm white LEDs should promote leaf expansion. Finally, after canopy closure, cool white LEDs should be used again to prevent
> excessive stem elongation. These effects could also be obtained by modulating the electrical current to red and blue monochromatic LEDs, thereby achieving different blue ratios without the requirement for two sets of LEDs.


http://cpl.usu.edu/files/publications/publication/pub__4124704.pdf

Last for now:
http://www.google.com/url?sa=t&rct=...GE8nGZuHmOJHKSA&bvm=bv.62577051,d.aWc&cad=rja


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## Greystoke (Jul 24, 2010)

I see Jeff is not letting the grass grow under his feet.
Meanwhile,
I’ve also been doing a little exercise.
Went to have a look at my file of fluorescent lights to see if some of them include the chlorophyll absorption wavelengths of 430nm, 453nm, 642nm and 662nm.
Most of them did, but to a varying extent. So I decided to construct a chart that shows the amount of the chlorophyll absorption wavelengths included in the light’s spectrum:








*Red+ Blue* equals the sum total of all four wavelength together in milli-Watt light output per Watt of electrical input power.
*Red/Blue* represents the power ratio between the red and the blue wavelength.
Next, I sorted the lights in order of “Red + Blue” descending values.
The result was a surprise, because for the first time I found my expensive champion bulbs right on top of the chart, except that *this time* I know why they are there:
*It means that the inclusion of the chlorophyll absorption wavelengths in the light spectrum is vital for the stimulation of our plants.
Conversely . . .
If these wavelengths are not or badly represented in the spectrum then it must be concluded that the light will not support plant growth.*


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## jeffkrol (Jun 5, 2013)

Greystoke said:


>


Next curiosity point I can't personally answer but I wonder which...



> I've spent maybe 1000-1500$ on T5 bulbs the last 2-3 years now. But I have a good handle on what works really well.


if any , of these correspond to Mr. Barrs favorites???... Singly or in mixes..???

Random selection of spectra:
Arcadia Freshwater:











Geissman Aquaflora"









3 Osrams.. and bulbs I can't read... 









GE 9325K:









corallife 10000K:

















Hagen life glo (Lumilux 965?)


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## jeffkrol (Jun 5, 2013)

Interesting one not on the chart:
Zoomed 5000K:








Very different than even Zoomed 5500K (top) or GE 5000k (bottom)


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## Greystoke (Jul 24, 2010)

These spectra don't tell you much, particularly Hagen's. I've found them to actually displace the peaks. I understand that they are artist's impressions. The guys that do adverts and - of course - they won't know where these peaks are supposed to be.


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## jeffkrol (Jun 5, 2013)

Greystoke said:


> These spectra don't tell you much, particularly Hagen's. I've found them to actually displace the peaks. I understand that they are artist's impressions. The guys that do adverts and - of course - they won't know where these peaks are supposed to be.


I'm not sure which ones are sales blurbs but as to the Hagen one.. NOT what I'd call a selling point spectrum.. The Russian ones I believe are independently generated..some of the others are from foster and Smith and probably ad generated. , if that means anything.. 
Yea it is good to question the accuracy, but I suspect the overall trends are fairly "honest"...

how about this one?? .............ack!!! ............... photoshop................................. anyways I'll leave it for reference and to remind myself to be more thorough..  









http://www.plantedtank.net/forums/showthread.php?t=137802


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## Hoppy (Dec 24, 2005)

Greystoke said:


> *It means that the inclusion of the chlorophyll absorption wavelengths in the light spectrum is vital for the stimulation of our plants.
> Conversely . . .
> If these wavelengths are not or badly represented in the spectrum then it must be concluded that the light will not support plant growth.*


Isn't it more accurate to say that if these wavelengths are not or badly represented in the spectrum then it must be concluded that the light will not support plant growth *as well as it would if the wavelengths were represented.* People do grow aquatic plants with a wide variety of light spectra, whether the plants grow well or just barely grow. Plants are a very adaptable form of life.


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## Greystoke (Jul 24, 2010)

You are right,
I think I jumped the conclusion. Bad habit. Perhaps I should've phrased it a bit differently, somewhat like:

_*"This suggests that the inclusion of the chlorophyll absorption wavelengths in the light spectrum is vital for the stimulation of our plants.
Conversely . . .
If these wavelengths are not or badly represented in the spectrum then the plants may struggle to grow."*_


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## Mr.ToR (Sep 16, 2016)

I'm about to order one of these two here and I'm trying to decide which one. 3red or 5red / 1blue.
https://www.aliexpress.com/item/SMD5730h-ydroponic-Systems-Led-bar-rigid-strip-Waterproof-DC12V-0-5M-Led-Grow-Strip-Light-Full/32559358418.html


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## jeffkrol (Jun 5, 2013)

Mr.ToR said:


> I'm about to order one of these two here and I'm trying to decide which one. 3red or 5red / 1blue.
> https://www.aliexpress.com/item/SMD...5M-Led-Grow-Strip-Light-Full/32559358418.html


Are you pairing these w/ something else? i.e white strings?

If alone the 1:3 ratio is more standard and less likely to cause "stringy" plants
1:5 ratio, when paired w/ white (blue based emitters) will be a bit easier to create a natural look..

somewhat related:
http://www.laserfocusworld.com/arti...wth-and-antioxidant-compounds-in-lettuce.html


> "Red light irradiation in the absence of blue light was effective at stimulating the biomass accumulation of lettuce plants; however, this lighting alone induced abnormal leaf shape and had a negative effect on polyphenolics and antioxidant levels," the scientists say. They recommend a mixture of blue and red LEDs to enhance lettuce-crop quality and yield in closed-type plant-production systems; the best results for lettuce arose from the blue:red ratios 35:65, 47:53, and 59:41.


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## Anon (Mar 16, 2014)

Hi Everyone,

I'm new around here (despite the 'Join Date'). And this is a fascinating thread. Why did it come to an abrupt end just over two years ago? Where's the sequel? Or am I missing something?

Anon


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