LED Quandary

[PetFlora]

LL, You seem very knowledgeable, until you said 'green isn't used by plants'

oh man, that is very bad 411

 

[Pass it Around]

I didn't copy and paste any of that but I am not nearly as intelligent as I'd like to be.

http://www.aliexpress.com/item/Free-shipping-300w-led-grow-light-full-spectrum-best-led-grow-light-2013-for-growing-mj/941775668.html?tracelog=back_to_detail_a

They say they use Epistar, Bridgelux, and Cree but I haven't confirmed. It is probably something like 150-200 watts because I thought LEDs would only use ~2/3 power to keep from frying themselves.

I'm just confused on the 2x2 flowering recommendation. Ed Rosenthal recommends half the HPS wattage when using LEDs . Quote,

"By tailoring the diodes’ light spectrum to plant requirements, LEDs can be more efficient PAR producers . HPS lamps deliver more total light per watt of input, but LEDs are twice as efficient in PAR light per watt as HPS lamps. That means a 200w LED lamp can be substituted for a 400w HPS lamp, and the 300w LED lamps can be substituted for 600w HPS lamps. The first generations of LED lamps did not emit an intense-enough light to support either active vegetative growth or flowering, but modern fixtures, which use higher-capacity diodes, have solved those early problems."

Rosenthal, Ed (2009-07-01). Marijuana Grower's Handbook (Kindle Locations 2166-2170). Quick Trading Company. Kindle Edition.

So I guess you need to use half the actual or rated watts of LED that you would use with HPS? Except I'm not sure if he's talking standard HPS distance lumens/par or air cooled or water cooled and how that compares to the distances from the canopy you'd be running with LED's hence the quandry.

On a side note he also recommends 5000 fc or more for flowering. The U.S. govt did some research on cannabis sativa and found with temps up to 30 celcius and 750ppm CO2 (they didn't test higher) the plant could handle 1500 micromols/m/s. foot candles translate differently depending on MH or HPS but I can't figure out how that translates to LEDs since the use a targeted spectrum and I'm not sure how much more efficiently it's absorbed. Here's the full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/pdf/12298_2008_Article_27.pdf

Half of the shit on their site is misspelled, how could you take any business seriously that has more spelling errors than a 60 page draft of an essay.

 

[LurchLurkin]

PetFlora, we had this discussion in another thread. You told me where to find the journal that said green was needed and then I only found one that said it wasn't. If you show me a peer reviewed article I will reconsider. I've done mass spectrometry before on plants personally, there's even a picture of one on the last page of this thread..green isn't really necessary.

Pass it around, I've spent time overseas in other countries to include Japan which is more developed and everyone makes the same mistakes. From menus in a restaurant to a Flesh Juice cafe (They were trying to go for fresh juice). All of the other countries I've visited make the same types of errors. To include the Philippines..and they learn English as a primary business language.

For one, English is hard as heck to learn. Secondly, I'm sure that we make the same mistakes in our attempts at Spanish or other languages of countries we trade with. When it comes down to it everyone has this national pride and think that you should speak their language so what we usually end up with is, "good enough" commerce translations.

I'm not a grower but simply interested in the science behind it. I can't vouche for this or that because I've never tried any of it. I'm not trying to be combative but I wont believe in fairy tales in a search for enlightenment so I'm just trying to glean information from you all and parse out the bias's to come to a more scientific understanding.

 

[hyroot]

PetFlora, we had this discussion in another thread. You told me where to find the journal that said green was needed and then I only found one that said it wasn't. If you show me a peer reviewed article I will reconsider. I've done mass spectrometry before on plants personally, there's even a picture of one on the last page of this thread..green isn't really necessary.

Pass it around, I've spent time overseas in other countries to include Japan which is more developed and everyone makes the same mistakes. From menus in a restaurant to a Flesh Juice cafe (They were trying to go for fresh juice). All of the other countries I've visited make the same types of errors. To include the Philippines..and they learn English as a primary business language.

For one, English is hard as heck to learn. Secondly, I'm sure that we make the same mistakes in our attempts at Spanish or other languages of countries we trade with. When it comes down to it everyone has this national pride and think that you should speak their language so what we usually end up with is, "good enough" commerce translations.

I'm not a grower but simply interested in the science behind it. I can't vouche for this or that because I've never tried any of it. I'm not trying to be combative but I wont believe in fairy tales in a search for enlightenment so I'm just trying to glean information from you all and parse out the bias's to come to a more scientific understanding.

university study for how green light drives photosynthesis

http://pcp.oxfordjournals.org/content/50/4/684.abstract

 

[PetFlora]

Looks like Hyroot has my back on this one.

Also, he proffered that mj seedlings do better under LEDs

And he's right there, too

Also, my reveg is doing amazing under the SPYDR 600

 

[guod]

PetFlora, we had this discussion in another thread. You told me where to find the journal that said green was needed and then I only found one that said it wasn't. If you show me a peer reviewed article I will reconsider. I've done mass spectrometry before on plants personally, there's even a picture of one on the last page of this thread..green isn't really necessary.
...
..

nice, but we are talking light spectrum here...

"Mass spectrometry (MS) is an analytical chemistry technique that measures the mass-to-charge ratio and abundance of gas-phase ions.[1] A mass spectrum (plural spectra) is a plot of the ion signal as a function of the mass-to-charge ratio. The spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules."

btw.
green light does not contribute much for energy harvesting, it's more a signal for light quality. study the crytochrome protein

https://www.google.de/search?q=cryptochrome&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:de:official&client=firefox-a&channel=sb&gfe_rd=cr&ei=Kd3zU-SkGciLOpXDgPAF#channel=sb&q=cryptochrome+green+light&rls=org.mozilla:de:official

 

[PetFlora]

Lets not confuse people, green is basically the nms between ~480-580

This range is like a super charger or turbo charger, helping the R/Bs to do their thing. The more RB's you have, the more 'green' you need to activate them

 

[LurchLurkin]

Ok, so I eat my words twice and apologize.

Plants definitely do use green light. Check out the "Higher Plants, Photosynthesis and Green Light: Myths Debunked" thread on ICMag. They cite that same study and then some. PetFlora you're not exactly right about "activating". There are different accessory pigments that absorb it and pass on the energy to chlorophyll..according to studies cited in that thread.

Also, I was a chemistry major not a biology major. I'm sorry I mixed up mass spectrometry and spectrophotometer.

So anyone know what spectrum is used by what was it..the XGS that used mostly white and some red?

 

[Yodaweed]

XGS used all white LEDs I think 3750k or something around that. RW used red and white and SGS used red and white.

 

[guod]

Lets not confuse people, green is basically the nms between ~480-580

This range is like a super charger or turbo charger, helping the R/Bs to do their thing. The more RB's you have, the more 'green' you need to activate them

your superduperturbo...
"Sometimes one may hear that plants don’t use green light for photosynthesis, they reflect it. However, this is only partly true. While most plants reflect more green than any other in the visible spectrum, a relatively small percentage of green light is transmitted through or reflected by the leaves. The majority of green light is useful in photosynthesis. The relative quantum efficiency curve (Photo 1) shows how efficiently plants use wavelengths between 300 and 800 nm. "

http://msue.anr.msu.edu/news/green_light_is_it_important_for_plant_growth

 

[LurchLurkin]

Ok so I read that...and it sounds like using green light is again not worth it. The green LEDs use more electricity to run.

"Twenty-five percent green light could substitute for the same percentage of blue light without affecting fresh weight. However, the electrical efficiency of the green LEDs was much lower than that of blue LEDs. "

 

[hyroot]

Ok so I read that...and it sounds like using green light is again not worth it. The green LEDs use more electricity to run.

"Twenty-five percent green light could substitute for the same percentage of blue light without affecting fresh weight. However, the electrical efficiency of the green LEDs was much lower than that of blue LEDs. "

I don't think you understood what you read. No possible way you read the whole thing that fast. Green wave lengths helps plants to pull photons from other regions so all pigments are being used..

 

[Greengenes707]

Ok so I read that...and it sounds like using green light is again not worth it. The green LEDs use more electricity to run.

"Twenty-five percent green light could substitute for the same percentage of blue light without affecting fresh weight. However, the electrical efficiency of the green LEDs was much lower than that of blue LEDs. "

You have so much to learn...
You are saying that because they are electrically inefficient that they are photosythetically inefficient as well. Those are two things totally different and irrelevant to each other in the case of is green needed for growth.
#1...green is useful for photosynthesis...bio-chem
#2...green LED's a less efficient than other nm's...electronics technology standpoint

Not that the efficiency of a green monochrome matters because you can get it in a white led of top efficiency.

Thanks goud for dropping the RQE chart.

Ask any company to supply a PAR footprint reading. That is the easiest way to compare any light tot any light. Quanta(photons)=bio mass(yield). After you see the output, then debate the spectrums of your choices. Spectrum dictates plant size, shape, the distribution of yield. Amount of photons are what give the general yield.

I(and others) am working with Ed for his next book currently. Talking, sharing info and grow data for my last few runs. Ed has 4 AT's that he was supposed to be using for the last few years but hasn't gotten anything done...busy man, don't take me the wrong way. My point is that he asks others for a lot of his info...specially area's that he has never dabbled in and probably won't at this point in his life. He finds credible and proven sources for his info, but just know that he hasn't tried everything himself. He's doesn't have his own grow rooms all over anymore...he writes books and what not now. His days of totally just him first hand experience is over. The world of led's in growing have changed 100 folds since just 2011...but some of us have been around the whole time and deeply invested because it is our passion. And just so happens like hyroot said...the best in the business is all right here on RIU. Seriously...THE BEST...any company, including NASA, would be lucky to have some of these ridiculously driven an educated LED builders/users/engineers from this site.

 

[LurchLurkin]

I did read the whole page linked that fast, and I've now finished reading the two parts more in depth.

I'm not saying that because it's electrically inefficient that it's photosynthetically inefficient as well. I just conceded that. I'm saying that in the study they got the same dry weight with or without the green light.

"We can conclude that adding blue light to the spectrum inhibits stem elongation and leaf expansion, while growing plants under only red light can increase stem length and leaf size. Twenty-five percent green light can substitute for 25 percent blue light without affecting fresh weight, but plants will be taller. "​

So if the fresh weight is the same and it costs more to add green LEDs then why add them if they don't increase weight?

Would you filter green out of the sun? No, it's free, and from what I'm reading it can be used and it even has better penetration than red or blue and that other pigments pick up the energy and pass it on to the chlorophyll.

A little copy and paste from IC Mag,
http://www.bio.net/bionet/mm/plant-e...er/001134.html

David R. Hershey dh321 at PGSTUMAIL.PG.CC.MD.US
Sun Nov 3 23:39:11 EST 1996

Quote:

Chlorophyll absorption spectra indicate a very low absorption of green compared to red or blue wavelengths. However, the photosynthesis action spectrum of an intact leaf indicates the rate of photosynthesis is roughly 60% as much with green light as with red and it may actually be higher than with blue (see Salisbury & Ross, Plant Physiology, 3rd, p. 185) Thus, leaves can use green light fairly effectively in photosynthesis. Some of the absorption may be due to accessory pigments. Chlorophyll in an intact leaf can also absorb green light much more effectively than the chlorophyll absorption spectrum (chlorophyll extract in a spectrophotometer) indicates. One reason is that although green light is absorbed with low efficiency, it has many chances to be absorbed because it is repeatedly reflected from cell to cell by the complex leaf geometry so it has many chances to be absorbed. Such geometry effects do not occur with chlorophyll extract in a spectrophotometer tube. This provides an excellent illustration of how in vitro can differ markedly from in vivo. .


Avoid Misconceptions When Teaching About Plants
David R. Hershey
An ActionBioscience.org original article

Quote:
Photosynthesis

A widespread misconception states that leaves reflect all green light and do not use green light in photosynthesis. Leaves often absorb more than 50% of the green light and use it efficiently in photosynthesis.8,22 The origin of this misconception is probably the chlorophyll absorption spectrum in textbooks. The chlorophyll absorption spectrum is a graph of light absorption versus light color. It shows that chlorophyll absorbs much red and blue light but little green light. However, accessory pigments absorb green light and pass that energy on to chlorophyll.​

I don't see anything about 'helping' to pull photons..there's just other pigments which will absorb it and pass it along if they have it.

BUT WAIT... There's more..and I'm eating my past words again since we're growing "flowers" and it appears green light is absorbed by cartenoids which are responsible for producing terpenes.

Quote:

http://www.leffingwell.com/caroten.htm

Carotenoids are the pigments responsible for the colors of many plants, fruits and flowers. They serve as Light Harvesting Complexes (with proteins) in photosynthesis...carotenoids are the precursors of many important chemicals responsible for the flavor of foods and the fragrance of flowers.
The primary odor constituents derived from carotenoids are C13 - C11 - C10 - and C9 derivatives formed via enzymatic oxidation and photo-oxidation of the various carotenoids found in plants, flowers and fruits. While other aroma constituents such as esters, terpenes, pyrazines, etc. are usually also present, these C9 to C13 compounds often are essential to the odor profile.​

So we can see that it is efficiently absorbed and utilized.

Avoid Misconceptions When Teaching About Plants
David R. Hershey
An ActionBioscience.org original article

Quote:

Photosynthesis
A widespread misconception states that leaves reflect all green light and do not use green light in photosynthesis. Leaves often absorb more than 50% of the green light and use it efficiently in photosynthesis.8,22 The origin of this misconception is probably the chlorophyll absorption spectrum in textbooks. The chlorophyll absorption spectrum is a graph of light absorption versus light color. It shows that chlorophyll absorbs much red and blue light but little green light. However, accessory pigments absorb green light and pass that energy on to chlorophyll.​

I don't see anything about 'helping' to pull photons..there's just other pigments which will absorb it and pass it along if they have it.

BUT WAIT... There's more..and I'm eating my past words again since we're growing "flowers" and it appears green light is absorbed by cartenoids which are responsible for producing terpenes.

Quote:
http://www.leffingwell.com/caroten.htm

Carotenoids are the pigments responsible for the colors of many plants, fruits and flowers. They serve as Light Harvesting Complexes (with proteins) in photosynthesis...carotenoids are the precursors of many important chemicals responsible for the flavor of foods and the fragrance of flowers.
The primary odor constituents derived from carotenoids are C13 - C11 - C10 - and C9 derivatives formed via enzymatic oxidation and photo-oxidation of the various carotenoids found in plants, flowers and fruits. While other aroma constituents such as esters, terpenes, pyrazines, etc. are usually also present, these C9 to C13 compounds often are essential to the odor profile. Above you will see a common oxidative fragmentation pattern (shown for beta-Carotene).
​

Other sources go on to say that they help with excess light dissipation and may be why current LEDs have been said to "burn" the plants. I didn't believe it before but perhaps because the cartenoids weren't getting enough light and so it allowed the plants to burn..if there was green light for the cartenoids the plants would have been fine?

 

[LurchLurkin]

I just got done speaking with LG-LED over in China, I asked them about producing an all white light at 3700 kelvin just like the XGS 190. He said they'd have to lower the amperage vs. their standard light so it wouldn't be as bright but would draw the same. He said they use epistar chips and would get back to me with the chip model number and more details when their engineer was back in. i.e. a 300 watt light would still draw about 185 which is very close to the XGS 190 except that it uses 5 watt chips instead of 3 watt. I think 5 watt chips are a waste of time for indoor growing because you should be doing SOG or SCROG due to the poor penetration of LED lights.

 

[RedCarpetMatches]

Do yourself a favor and go full spectrum. Check out the CMH thread from your other forum.

 

[LurchLurkin]

That's twice someone has mentioned CMH, what does that acronym stand for?

Edit: Sounds like Ceramic Metal Halide, but a search for that in the title brings 1834 results

 

[RedCarpetMatches]

That's twice someone has mentioned CMH, what does that acronym stand for?

Edit: Sounds like Ceramic Metal Halide, but a search for that in the title brings 1834 results

https://www.icmag.com/ic/showthread.php?t=72215

860w and 315w LEC kit journals here too. Can't go wrong with the 930s...my next purchase.

 

[LurchLurkin]

Am I spot on or not?

Hi Anna Lee,

We spoke before about the 1200 watt mars ii light. I have decided that is not the best choice in lighting.

My reasons for this are because of:
1. Spectrum - I know if you look at a spectrophotometric analysis of photosynthesis it looks like plants don't really use green. In fact they absorb green about 60% as well as they absorb red.

a. The light bounces repeatedly against the structure of the plant giving it more chances to be absorbed.

b. Cartenoids - in the plant which are in a much smaller amount then chlorophyll DO absorb green very well. They pass excess energy onto the chlorophyll and they are responsible for terpenes (smell) as well as flower taste. They also will dissipate excess energy and are the reason your LEDs have been shown to bleach plants when they are too close. If your lights contained green I do not think this would be an issue.

2. Watts - 5 watt chips do offer more penetration but they are much more expensive. They also require larger heat sinks further driving up the production costs.

a. The most efficient indoor style of grow is Sea of Green or Screen of Green. Since the canopy is so even and lush the lights do not need penetration and can be kept very close so that light is not wasted. 3 watt chips are most adequate for this.

3. Size - The larger overall wattage of this light means that fewer are needed, but one could purchase 4 300 watt 3 watt chip LED panels for the price of one Mars ii 1200 watt. Having more lights to cover a smaller area allows for better light distribution over the canopy and will result in better results when flowering.

The problem is that green LEDs are inefficient and use more electricity to run. The solution is to use a high quality white LED. It contains the entire spectrum of lighting which is very beneficial to the plant. I understand white is also not as efficient as red LED's but the benefits definitely outweigh the negatives.

I've spoke with Smoke Sara on 420 Magazine and no one has tried 3700 Kelvin as the entire spectrum before. This is a warm spectrum that is very good for promoting flowering.

The lack of a blue spectrum makes this a light which would not be very good for vegetative growth because without blue the plant will tend to stretch. This is not an issue for anyone who will put their clones right into flower. If you were to produce other models you may want to include some blue LEDs which operate on a switch to make the light suited for both vegetative and flowering as the blue lights will discourage plant stretch and decrease internodal spacing.

I spoke with Alva about producing some all white LED panels and asked her to email me a quote for them. She said you would be using epistar chips and I also wanted to know the model number so that I could check to see the quality of their color myself before I made any recommendations. I can check it with a color temperature reader. She said she was waiting for the Engineer to get back but I have not received an email.
I find your 300w 3 watt chip light panel a suitable carcass for my design which could only be improved if the panel were square in shape but that criteria is subjective to the growing space. http://www.aliexpress.com/item/2014-new-300w-led-grow-lights-panel-high-power-led-grow-light-full-spectrum-led-grow/1836287852.html

I am not an electrical engineer but I am a chemical engineer. I am not completely knowledgeable on LED lighting and I'm unsure if you wire your LEDs in series or in parallel. I feel that the highest quality LED which can be provided is made by Cree.

If they are to be wired in parallel the ordering number for the Cree LEDs is: MLCAWT-A1-0000-0000E5

If they are to be wired in series the order number for the Cree LEDs is: MLCSWT-A1-0000-0000E5

Cree produces very high quality LEDs which have been shown to provide superior results for growing plants.

 

[LurchLurkin]

She said with an order of 200 units she could produce them but with the higher quality leds the price would be steeper. She would have to source the leds and speak with her plant manager to determine a price. Is this something you all would be interested in and should I start a new thread asking who would to commit to buying how many? Once there was a commitment for 200 their usual turn around time would be about a month. Just trying to get you all a good deal before someone patents it and rips you off.