Importance of 460nm red LEDs?

[RackitMan]

Here is something very confusing to me. Many LED proponents loudly proclaim the need for 460-470nm red LEDs over the cheaper 630nm LEDs. I understand that this better coincides with the accepted chlorophyll B absorption peak.

So far so good.

LEDs veg very well given appropriate wattage & color.

So far so good.

LEDs do not compare (generally) to HPS flowering as far as yield. (Please - let's not go off in that direction here. Thank you!)

OK, here is the enigma: HPS has a ton of yellow. No LED grow lamps contain yellow. HPS has lots of orange. Some LED lamps contain a little orange. HPS has virtual no Deep Red or Far Red and do very well - yet this is somehow necessary for a good flowering LED light. Even 'inferior' 630nm red is relatively low in HPS.

Any SCIENTIFIC opinions on this major discrepancy?

The only thing I can come up with is that plants rapidly adapt to the core frequency of the light provided which would put in question the whole currently accepted Plant Absorption spectrum.

[stra8outtaWeed]

Here is something very confusing to me. Many LED proponents loudly proclaim the need for 460-470nm red LEDs over the cheaper 630nm LEDs. I understand that this better coincides with the chlorophyll B absroption peak.

So far so good.

LEDs veg very well given appropriate wattage & color.

So far so good.

LEDs do not compare (generally) to HPS flowering as far as yield. (Please - let's not go off in that direction here. Thank you!)

OK, here is the enigma: HPS has a ton of yellow. No LED grow lamps contain yellow. HPS has lots of orange. Some LED lamps contain a little orange. HPS has virtual no Deep Red or Far Red and do very well - yet this is somehow necessary for a good flowering LED light. Even 'inferior' 630nm red is relatively low in HPS.

Any SCIENTIFIC opinions on this major discrepancy?

The only thing I can come up with is that plants rapidly adapt to the core frequency of the light provided which would put in question the whole currently accepted Plant Absorption spectrum.

for one 460nm is blue 630nm is red and 660nm is deep red:jointsmile:

so my advice here is to look at my LED's which have 3500k warm white that do appear yellow to the eye and look at my grows! :smokin:

i get great yields for the wattage i put over my plants...but the difference in my units are they use 3w diodes..not the 1w UFO style!

plus the pattern of LED''s are spread out over a 4" x 40" window creating light from many different angles!

too many folks get caught up in the more power of a single panel and applying the same thought as HID...1000w is better than 400w...in LED's it is all about the quality and power of the LED and having a good distribution so you can keep them as close to the plants as possible. This does not work with a LED panel that has all of the LED's bunched close together like UFO or similar lights....if you lower them close it shrinks the coverage so you have to lift higher to increase the light footprint and then lose effective flowering...this is why many say LED's do not work in flower and it is only because of design.

Since i have been flowering with my LED's it has increased the oil prodution and has made my meds more potent...i would love to get my meds analyzed for THC/CBD and CBN ratios because i can feel the difference in my meds. I had spinal cord injury and suffer from severe neuropathy and most peoples meds do not even touch my pain...so i will NEVER go back to HPS!:thumbsup:

plus no heat...no bulbs to buy again...my lights will pay for themselves in energy savings alone.

i have finished 3 grows to completion with yields of 390gr 437gr 357gr with 450w of LED's... the 4th will be tallied in about 2 1/2 weeks:jointsmile:

[RackitMan]

Apologies for the typo: 460 -> 660.

[RackitMan]

Hey Str8,

While I am ultimately interested in results and would like to read more about your grows; as an engineer, I need to know more about the science behind a particular design and the science as currently presented does not jive.

[stra8outtaWeed]

Hey Str8,

While I am ultimately interested in results and would like to read more about your grows; as an engineer, I need to know more about the science behind a particular design and the science as currently presented does not jive.

i'm not an engineer but my results are real world...that is what is important to me:thumbsup:

the one thing i have learned is 660nm is important in getting a good flower run and they are the most expensive diode so many makes of LED lights just selling price alone do not have good 660nm diodes.:hippy:

so the cheap ones are really only good to grow in veg with...this is like comparing CFL to HID:smokin:

[RackitMan]

"the one thing i have learned is 660nm is important in getting a good flower run"

Almost every single commercial grower and most home growers get great flowers (HID) with virtually no 660nm, yet you see no puzzle?

[stra8outtaWeed]

i grew with 2 1000 watt hps...digital ballasts and hortilux bubls and my yields are very close and my meds are stronger...whats to figure out? :D

i don't need science to tell me my plants are healthier and producing better meds...there are a few folks on here who may be able to explain your question but again my results tell me everything. you are welcome to look at my albums and grow log. :hippy:

plus i am only growing with half the power i did from before and no heat to worry about or cooling!:jointsmile:

[khyberkitsune]

Almost every single commercial grower and most home growers get great flowers (HID) with virtually no 660nm, yet you see no puzzle?

http://www.hidhut.com/catalog/images/600HPS%20Lamp.jpg

I see TONS of 660 there for HPS. In fact there are almost NO lamps (besides monochromatic ones) that do NOT have 660 emissions of some sort.

[DreadedHermie]

I understand that this better coincides with the accepted chlorophyll B absorption peak.


That's incorrect. 660nm is closer to Chlorophyll A's red absorption peak.


LEDs do not compare (generally) to HPS flowering as far as yield. (Please - let's not go off in that direction here. Thank you!)

That's also incorrect. Check the European cannabis boards, especially the Dutch and Spanish boards. There are numerous documented side-by-sides where 1K watts of LED easily surpasses 1K watts of HID. Their only bitch is how expensive quality emitters are. Is uw Nederlandse taal goed?

Rackitman, if you don't want to hear from people who've successfully flowered cannabis under leds, who do think is going to give you any insight about 660nm? Some dork with a 14 watt China panel?


HPS has virtual no Deep Red or Far Red and do very well - yet this is somehow necessary for a good flowering LED light. Even 'inferior' 630nm red is relatively low in HPS.

Also incorrect. The radiation emitted by HPS even includes a generous amount of non-visible IR, AKA "heat."

[attachment=o240903]

[attachment=o240902]

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[attachment=o240905]

[jtsik330]

The graphs sell the LED's themselves. Urban grower has an article showing the same graphs and the average spending cost of both HPS and LED and its swaying me towards LED's day by day. Ventilation is getting expensive these days. :)

[Weezard]

That's incorrect. 660nm is closer to Chlorophyll A's red absorption peak.



That's also incorrect. Check the European cannabis boards, especially the Dutch and Spanish boards. There are numerous documented side-by-sides where 1K watts of LED easily surpasses 1K watts of HID. Their only bitch is how expensive quality emitters are. Is uw Nederlandse taal goed?

Rackitman, if you don't want to hear from people who've successfully flowered cannabis under leds, who do think is going to give you any insight about 660nm? Some dork with a 14 watt China panel?



Also incorrect. The radiation emitted by HPS even includes a generous amount of non-visible IR, AKA "heat."

[attachment=o240903]

[attachment=o240902]

[attachment=o240904]

[attachment=o240905]

I concur on all counts.
Good correction DH. :)
"You must spread, yadayada"

Aloha y'all
Weeze

[stra8outtaWeed]

i was waiting for you guys to chime in...rep to all:thumbsup:

i es no tekneecal Weezard...but i do's know how to grow:D

[khyberkitsune]

Was wondering when the others would come in to weigh in. :)

Hi guys! :hippy:

[RackitMan]

http://www.hidhut.com/catalog/images/600HPS%20Lamp.jpg

I see TONS of 660 there for HPS. In fact there are almost NO lamps (besides monochromatic ones) that do NOT have 660 emissions of some sort.

Seems people here are totally missing my point:

The watt per watt LED grow match the HPS grow with 80% deep red and no yellow while the HPS has 80% yellow/orange and only maybe 5% deep red.

The current science tells us HPS should be an epic fail in comparison - and yet it doesn't.

Is no one else truly curious? Methinks there is something critical here that we are overlooking that could help in future LED designs.

[stra8outtaWeed]

you have answered your own question.....this is why LED's are more efficient with more than 80% of the light used by the plant and HPS only about 20 - 30 % of the light absorbed is actually used...this is why less wattage can match production of HPS...LED's hit the main lighting wavelenghts with little energy wasted:smokin:

not to mention the energy for cooling costs...thats why it takes 1000w HPS to get good results!:thumbsup:

[RackitMan]

you have answered your own question...:

Not even close. If the science as presented was complete and accurate, and 80% of HPS light was wasted then LEDs would be outperforming HPS by a huge factor.

Not happening.

I am not challenging you guys as you seem to think, but there is definitely a piece of knowledge missing.

[stra8outtaWeed]

as i stated i do not need science to tell me my meds are better....i have incredible pain from SCI and when i can match production and have more potent meds...then LED's are blowing HPS out as i said earlier I WILL NEVER GO BACK TO GROWING WITH HPS....i am producing outdoor quality product with indoor controls basically!

[khyberkitsune]

Not even close. If the science as presented was complete and accurate, and 80% of HPS light was wasted then LEDs would be outperforming HPS by a huge factor.

Not happening.

I am not challenging you guys as you seem to think, but there is definitely a piece of knowledge missing.

There is nothing missing, the math hasn't been expressed and there's still one important unit that hasn't been discussed.

Take a look at the light spectral chart - 80% is emitted in yellow/green, 20% in the blue/red.

Out of a 400W HPS, 320 watts of light are from yellow/green. 80 watts blue/red. This is why 90w UFO panels have the equivalent (even as stated on my panels) "Photosynthetic power" - only the honest panel makers refuse to say "Get the same yield as" because that is misleading.

The DIFFERENCE is that the HPS emits a higher photon flux density even for just those 80 watts of actual blue/red versus typical 1W led panels. Also, the angle of emission of LEDs directly determines the photon flux density - the wider the beam angle the less dense the flux of photons. You want the penetration power of a 400w HPS out of a panel of 1W diodes? Put the diodes down to a 30 degree beam to increase the photon flux and thus the penetration power.

But even watt-for-watt 400w LED in a tight panel will smash 400w HPS for yield. 400w 100% usable plant power versus 400w 20% usable plant power. Add in the fact they last longer and the entire thing is a long-term win situation.

[thepaan]

I want to show you an e-mail I got recently.


I just went back to look at Fig. 7 of the PDF in:

The Photosynthetic Action Spectrum of the Bean Plant -- Balegh and Biddulph 46 (1): 1 -- PLANT PHYSIOLOGY (http://www.plantphysiol.org/cgi/reprint/46/1/1)

The action curve mostly ranges from 72 to 113 molecules of CO2 utilized
per 1,000 photons.

Typical red LED light with peak wavelength of 635 nm appears to me,
according to that curve, to achieve utilization of 108 molecules of CO2
per 1,000 photons incident upon the leaves.

These photons have average eergy close enough to 1239.7/635 electron-
volts each, which is 1.952 electron-volts.

Multiply 1.952 by 1,000/108, and so far it looks like 18.075
electron-volts of energy in the form of red LED light is required to
convert one CO2 molecule and one water molecule into one O2 molecule and
carbohydrate.

To convert this to joules per mole, multiply by Faraday's Number, which
is 96,485 coulombs per mole. This indicates that 1.744 megajoules of red
light from LEDs having peak wavelength of 635 nm is required to remove one
mole (44 grams) of CO2 from the air.

Good LEDs of this peak wavelength are around 25% efficient. This means
about 7 megajoules, or about 1.94 kilowatt-hours, of electric energy must
be delivered to such red LEDs to remove 1 mole (44 grams) of CO2 from the
air.

Keep in mind that these red LEDs usually have their dominant wavelength
mentioned more than their peak wavelength. The dominant wavelength is a
color specification and is in the mid 620's of nm for these red LEDs.
This usually appears as a slightly orangish shade of red.

====================================

I am repeating these calculations for two other LED wavelengths used for
growing plants:

660 nm: My eyeball estimate is that that one's spectrum achieves 109
molecules CO2 utilized per 1,000 incident photons, rather than 108. A 660
nm photon has 1.878 electron-volts of energy rather than 1.952. So light
energy requirement to remove 1 mole of CO2 from the air is 1.744
megajoules * (108/109) * (1.878/1.952), which is 1.663 megajoules.
I know of one manufacturer of such LEDs achieving about 25% efficiency
(LEDEngin). That indicates about 6.7 megajoules (about 1.85
kilowatt-hours) of electrical energy must be delivered to these 660 nm
LEDs to remove 1 mole (44 grams) of CO2 from the air.

Since plants have some requirement for blue light, I am repeating these
calculations again for 450 nm, from a Philips-Lumileds "Luxeon Rebel" LED
of "Royal Blue" color. My "eyeball estimate" of photosynthetic action by
that LED's spectrum is 92 molecules of CO2 per 1,000 photons. The average
energy per photon here is 2.75 electron-volts.

So, 1.744 * (108/92) * (1.952 / 2.75) means about 2.88 megajoules of
such blue LED light are required to remove 1 mole (44 grams) of CO2 from
the air. It appears to me nowadays that a top rank royal blue Luxeon
Rebel is about 30% efficient at a conservative current of 350 milliamps.
That means 9.6 megajoules, or 2.67 KWH, of electrical energy must be
delivered to these LEDs to remove 1 mole of CO2 from the air.

Red LEDs need conservative amounts of current and excellent heatsinking
to achieve 25% efficiency. LEDEngin 660 nm red LEDs probably achieve 25%
efficiency at 350 milliamps, possibly at 700 milliamps. The shorter
wavelength orangish red ones usually achieve 25% efficiency at 500 mA at
the most, preferably 350 mA.

Growth is directly proportional to the rate of photosynthesis. The rate of photosynthesis varies based on what wavelength of light the plant is exposed to. Anyway, theres some math for you. The spectral output for an HPS can be approximated and calculated for every 10 nm or so, such that you get the ammount of CO2 reduced per whatever-you-want-to-measure-your-light-output-in (I suggest a spreadsheet or some such thing) then compare to deep red LED.

[RackitMan]

Interesting. So if I am understanding you or the article properly, it is not so much that a plant specifically needs 660nm light, it is just that that wavelength gives the greatest photon->CO2 conversion rate.

Hypothetical: So if a monochromatic LED could convert 50% of its electrical energy to yellow light, it would outperform a monochromatic LED that could only convert 25% of its electrical energy to deep red light. Is this (more or less) correct?

Or does our fave plant require a SPECIFIC trigger at 660nm that cannot be compensated for by other spectra?

[khyberkitsune]

"Hypothetical: So if a monochromatic LED could convert 50% of its electrical energy to yellow light, it would outperform a monochromatic LED that could only convert 25% of its electrical energy to deep red light. Is this (more or less) correct?"

Only if the plant is capable of using the Emerson effect to downshift that yellow light to another energetic wavelength it can use. Very few plants have this capability, most of them that do have it are aquatic plants. Cannabis is not one of them, it is like most terrestrial plants in that it uses the Emerson effect for downshifting blue into other wavelengths they require since upconversion from red requires an active power input and frequency modulation - something plants just can't do (at least on this planet.)

[stra8outtaWeed]

Interesting. So if I am understanding you or the article properly, it is not so much that a plant specifically needs 660nm light, it is just that that wavelength gives the greatest photon->CO2 conversion rate.

Hypothetical: So if a monochromatic LED could convert 50% of its electrical energy to yellow light, it would outperform a monochromatic LED that could only convert 25% of its electrical energy to deep red light. Is this (more or less) correct?

Or does our fave plant require a SPECIFIC trigger at 660nm that cannot be compensated for by other spectra?

so all of the above info is useless...i correct you in the beginning...you claim typo..ha....you are wrong on 660nm with your chloriphyl b statement..i explain with real world results that you can't wrap your ears around and it is the peak absorption rate for photosynhtesis...we explain the inefficiencies and you still don't get it...it takes some scientific jargon to get you to point and you still miss the peak creation of photosynthesis is 660nm and adding CO2 will substatially help with yield...that is real world language!

to Paan~thank you for your post:thumbsup:

[thepaan]

Besides using light to drive photosynthesis, specific wavelengths are required for things like avoiding stem elongation (we want short fat plants, not tall skinny plants), proper leaf shape/size/orientation, stomatal opening (the pores underneath leaves that allow the plant to breathe), and flowering (in some plants). Some responses like flowering vary widely from plant to plant while others like stem elongation and stomatal opening are almost universal. Most of those responses can be had with minimal amounts of blue light (again, it depends on the plant)

Besides all that, I believe you have the right idea: A yellow LED of a high enough efficiency could be more efficient at driving photosynthesis than a deep red. Unfortunately, there is no such thing as a yellow LED - only red or blue LEDs with phosphors to convert a portion of the light. As such they will never be as efficient as the base LED.

If we look at our bean plant data from before (if someone has this data for cannabis I'd love you forever) we can see that 700 nm light causes the plant to consume about 34 molecules of CO2 for every 1000 photons and 650 nm light causes the plant to consume about 103 molecules of CO2 for every 1000 photons. From this, one might guess that given 1000 photons of 700 nm light and 1000 photons of 650 nm light then the plant would consume 137 molecules of CO2, but actually it consumes a bit more. This effect was discovered in 1957 by Robert Emerson. This effect exists because all higher plants have two photosystems and a full photosynthetic cycle (not sure if I'm saying that correctly) can not proceed unless both systems are stimulated. photosystem I, containing more chlorophyll a, uses the 700 nm light more efficiently while photosystem II, containing more chlorophyll b, uses the 650 nm light more efficiently.

Anyway, I'm using about 20% 460 nm blue LED and the rest 660 nm red.

[thepaan]

Oh wow you just set an alarm off in my brain.

I was reading some article the other day about greenhouse growing of spinach and strawberries and some other things. In all cases they were able to significantly reduce the amount of light required by increasing the concentration of CO2 in the air. This is because the last part of photosynthesis, which takes CO2 from the air and converts it to sugars will also take in Oxygen and use it for photorespiration. Photorespiration allows the plant to sustain itself but doesn't really let it grow. In normal air a molecule of oxygen is used for every molecule of CO2 but the rate of CO2 can be increased by increasing its concentration in the air. This is important because as of now, it is more expensive to provide supplemental lighting (both the initial and electrical) than it is to fill a growing chamber with additional CO2.

[stra8outtaWeed]

Again...thank you for your input! it is well explained!:thumbsup:

[RackitMan]

Anyway, I'm using about 20% 460 nm blue LED and the rest 660 nm red.

For the whole grow or just for flowering? I used strictly a 50w blue LED panel last year for veg, no red or white, and it worked very well for my two medium small plants which I found surprising.

How many watts of LED do you find necessary per square foot (I realize it depends greatly on the output and wattage of the LED) for a decent grow and which manufacturer/emitter wattage did you choose?

I see E-Bay has some 20w 630nm LEDs for $16 to $25 or I can buy some 10w 660-670nm emitters for $30 at Mouser. As this is strictly for my own small (2' X 2') grow, intital cash outlay is more important than optimal efficiency. Your thoughts on this?

[khyberkitsune]

"Unfortunately, there is no such thing as a yellow LED"

I manufacture 570-580nm diodes.

"This is because the last part of photosynthesis, which takes CO2 from the air and converts it to sugars will also take in Oxygen and use it for photorespiration."

Atmospheric CO2 will not have an effect on the O2 concentration in the soil or medium - roots import oxygen, leaves export oxygen. They were able to reduce the light required with the CO2 increase due to the current effectiveness of LEDs, and the fact you don't have yellow or green light inhibiting other processes - you remove one limitation only to hit another one - they ran into the CO2 barrier and had to supplement.

Roughly 20 photons = 1 molecule of sugar. They didn't have enough CO2 for the consumption/sugar production part of the Krebs cycle.

[khyberkitsune]

For the whole grow or just for flowering? I used strictly a 50w blue LED panel last year for veg, no red or white, and it worked very well for my two medium small plants which I found surprising.

How many watts of LED do you find necessary per square foot (I realize it depends greatly on the output and wattage of the LED) for a decent grow and which manufacturer/emitter wattage did you choose?

I see E-Bay has some 20w 630nm LEDs for $16 to $25 or I can buy some 10w 660-670nm emitters for $30 at Mouser. As this is strictly for my own small (2' X 2') grow, intital cash outlay is more important than optimal efficiency. Your thoughts on this?

For your 2x2 room a single 90w panel would well more than suffice.

Going over 5w for emitter power is pointless, you start hitting multi-chip emitters and they're fairly inefficient as it is.

eBay-found emitters are typically bottom-bin and way off-spec (you expect 460nm, you get 480nm instead.)

Mouser is overpriced, you're better off buying direct from LEDEngin if you're going that route.

[ForgetClassC]

Not even close. If the science as presented was complete and accurate, and 80% of HPS light was wasted then LEDs would be outperforming HPS by a huge factor.

Not happening.

I am not challenging you guys as you seem to think, but there is definitely a piece of knowledge missing.

You need to read, and no I'm not saying I'm an LED expert or a lighting expert, but like DH said, the comparisons you are looking at don't seem to be of equal wattage. When LED's and HID's are matched by wattage, LED's destroy. Why not try and find a grow of 450W of HID and compare it to stra8's 450W of LED. No comparison. What you are saying pretty much is that HID's waste alot, and you keep saying that. And what you also keep saying is that LED's do not waste, because like you said, 1000w HPS lights not fail, but 450w LED's do the same work, so meaning, that the HPS light is LESS EFFICIENT......If I'm too high or not enough, someone tell me, but that's pretty much what I've been reading.

-C

[Weezard]

Bingo!:thumbsup:
Give dat guy a beeg spliff!

Weeze

[Weezard]

Aloha Khyberk,

You said; "Going over 5w for emitter power is pointless, you start hitting multi-chip emitters and they're fairly inefficient as it is. "

I have to disagree
In truth, everything from 2W. on up are multiple emitters.

My hands-on experience indicates that 5W. chips are very good, but 15W emitters are superior.
For actual growing that is.
I'll leave the why of that for the mathturbaters.:D

And, I gotta ask.
Did you ever try buying direct from Ledengin?:)

They sent me to mouser's:(

No pickin' fights, jus' stating facts.:)

Aloha, Y'all

Weezard

[DreadedHermie]

I'll betcha Ledengin would sell the 15W 660's now, because Mouser isn't carrying them anymore. Sales / cust service is ext. 115. :D Question is, what's their minimum order?

[khyberkitsune]

Aloha Khyberk,

You said; "Going over 5w for emitter power is pointless, you start hitting multi-chip emitters and they're fairly inefficient as it is. "

I have to disagree
In truth, everything from 2W. on up are multiple emitters.

My hands-on experience indicates that 5W. chips are very good, but 15W emitters are superior.
For actual growing that is.
I'll leave the why of that for the mathturbaters.:D

And, I gotta ask.
Did you ever try buying direct from Ledengin?:)

They sent me to mouser's:(

No pickin' fights, jus' stating facts.:)

Aloha, Y'all

Weezard

None of my 3 or 5w emitters (used for biofuel algae production) are multi-emitter. They are a single chip with a massive tweaked lambertian emission pattern. Photon flux density is more efficiently increased by making more powerful single emitters rather than using valuable die real-estate making multi-emitter chips, primarily because the chips in multi-emitter diodes are spaced apart and create a 'ghosting' effect. Sure you get more chips out of a multi-emitter size but the costs increase and flaws happen much more often as you scale down as well. Just one issue one deals with when working in the semiconductor industry.

Savage Marine uses 10w single-chip emitters for their lights on their boats, multi-chip emitters just created consistency problems in light, with different emitters fading at different rates, drastically changing the emissions. Those are probably some of the best I've seen in a while, with their irradiant output per watt being better than most 15w multi-emitters.

I think LEDEngin sent you to Mouser because you weren't likely a major manufacturer of a product - LEDEngin prefers bulk sales versus smaller retail, despite the higher profit margins direct retail offers, and would prefer the recognition from retail resellers than direct retail. My company works somewhat the same way, unless you're in a high company position (engineering, research, or C*O) or are a reseller, we will usually direct you to one of our retailers or to our website, unless you have a very specific custom request, in which case you deal directly with me, and if need be I fly out there.

I will concede that most 3w+ LEDs are multi-chip, but you can find single-chip emitters, and they are (so far) offering better performance than higher-powered multi-chip LEDs.

[khyberkitsune]

I'll betcha Ledengin would sell the 15W 660's now, because Mouser isn't carrying them anymore. Sales / cust service is ext. 115. :D Question is, what's their minimum order?

One minute, I'll call and find out since I have a line with them already.

[khyberkitsune]

One minute, I'll call and find out since I have a line with them already.

Direct extension 115 doesn't work, but option 3 always does :) I left a message, nobody answered.

[stra8outtaWeed]

I'll betcha Ledengin would sell the 15W 660's now, because Mouser isn't carrying them anymore. Sales / cust service is ext. 115. :D Question is, what's their minimum order?

hey Hermie...look into my album on pictuer of my lights and hit my email...got a few things i'd like to discuss with ya if ya don't mind:D

[Weezard]

"I will concede that most 3w+ LEDs are multi-chip, but you can find single-chip emitters, and they are (so far) offering better performance than higher-powered multi-chip LEDs. "

Mahalo, saved me diggin' out da cyclops.:D

I do appreciate your point of view and approach, as a producer.
"offering better performance "
As a personal grow amateur, ainokea 'bout "da last drop":rastasmoke:

I cut my power bill by 2/3rds and grow bodaceous meds.
'snot da mos' efficient, but it works a treat!
Have no intention to market any of it.
I jus' givem, make da world a li'l mo' betta, yah?:hippy:

Aloha, -not jus' a word.

Weezard

[thepaan]

For the whole grow or just for flowering?

For the whole grow. Flowering is accomplished by changing the length of the night (long nights induce flowering in most cannabis strains). The problem with this is short days don't give as much light as long days and we want as much as possible for maximum growth (we aren't growing leaves during flowering but more light still makes bigger flowers). Since this is a phytochrome response, we can try to a) avoid visible red or 2) supplement with far red around 730 nm. I've never tried either. There is a range of response for some plants (all the way into the blue) but others require specific wavelengths (around 660 nm) to induce flowering and likewise the reverse conversion isn't always exactly at or exclusively 730 nm. I don't know the specifics for cannabis.

Google book - scroll down to chapter 1, page 3:
Marijuana Botany: Propagation and ... - Google Books (http://books.google.com/books?id=_aK7dTNS1qkC&printsec=frontcover&dq=isbn:091417178X&cd=1#v=onepage&q=&f=false)

More on phytochrome:
floinduc (http://www.public.iastate.edu/~zool.533/lectures/flower.htm)


How many watts of LED do you find necessary per square foot?

I put together this spreadsheet a while ago to figure out exactly that. Start on the 22moles/m2/day (E,39) and adjust from there. You will need to know the light output of each LED in watts and the area in square meters (C60).

https://spreadsheets.google.com/ccc?key=0AlIFMFqXkch9dEdxS3NNd1VuLVJTVEJmSmZ5MzhzZ lE&hl=en


Also, the path oxygen takes to the thylakoids is irrelevant to the point. Rubisco will react with either oxygen (photorespiration) or carbon dioxide (photosynthesis). When the availability of either gas is altered it directly alters the probability of each function. I was wrong, however, on the 1 for 1 ratio. I meant to say 3 CO2 for each oxygen but in actuality I can't recall if it is exactly 3 or a little higher. And the LEDs too: I've never really looked at yellow LEDs too much I just (ass)umed they were like white LEDs.

You got me again, khyberkitsune. :P

[thepaan]

I just remembered where I read that: Molecular Mechanisms of Photosynthesis (ISBN 9780632043217), page 182. "...the rate of carboxylation is only about three times the rate of oxygenation under normal physiological conditions."

[thepaan]

Aaaaaand I finally found that greenhouse article again. Skip to page 18 (or read the whole thing like I did :P).

http://www.nyserda.org/InnovationsInAgriculture/Presentations/Session1_April16/Lou_Albright.pdf

[RackitMan]

For the whole grow. Flowering is accomplished by changing the length of the night (long nights induce flowering in most cannabis strains).

I understand this, but are you saying the oft-quoted "more blue for veg; more red for flowering" is not correct?

Seems you have the 'metal halide for veg and HPS for flower' meme, and the latest 'one light (CMH or properly designed LED) for the whole grow.

Now, I am not sure how much the solar spectra changes (filtered through the atmosphere) from spring to fall - if in fact we are somewhat attempting to
mimic nature.

Just lots of conflicting 'information' floating around that I am seriously trying to grok.

Thanks for all your scientific references! :thumbsup:

[khyberkitsune]

"Now, I am not sure how much the solar spectra changes (filtered through the atmosphere) from spring to fall - if in fact we are somewhat attempting to
mimic nature."

Insolation changes very little at the equator and swings a bit wider from the tropics up to about 55 degrees latitude north or south. The only real change is the angle at which the sun hits our atmosphere which adjusts refraction and dispersion, and this happens due to Snell's law (going from vacuum of space to atmosphere) and our orbital position/axial tilt.

My panels are designed to emulate this effect in separate modules. Maybe another redesign will allow for adjustment to suit individual plant varieties but as far as general-purpose seasonal emulation goes I've probably got the best available.

[thepaan]

are you saying the oft-quoted "more blue for veg; more red for flowering" is not correct?

More or less, yes.

As khyberkitsune said, the spectral content of light leaving the sun doesn't change; only the portion making it through the atmosphere does. I never considered if that would affect growth since I have never seen any studies along those lines. If I had to guess, I'd say it doesn't matter but honestly, I'm not sure.

Back to the question. I don't know why so many people think they need to change the color of the light, though I suppose it works since so many people do it. This is my guess: The cause of flowering (from light) clearly has nothing to do with blue wavelengths because phytochrome simply does not react to blue light. We are left with red light as the causal factor. Since cannabis is a short-day plant (flowering when the days become short or, long-night) and the day length is determined by duration of red light, then exclusive blue light (suggested for vegging) would cause the plant to reach the flowering stage more quickly due to a phytochrome-perceived perpetual night (is this the desired result?). But even MH should have enough red light to cause the day to be perceived and thus to postpone flowering. This is why I can't figure out why people say to use blue light. You can keep the plant from flowering by just leaving the lights on longer. The only advantage I can think of would be to give the plant more light but make it think it has a short day but that is not what they are doing.

[khyberkitsune]

More or less, yes.

As khyberkitsune said, the spectral content of light leaving the sun doesn't change; only the portion making it through the atmosphere does. I never considered if that would affect growth since I have never seen any studies along those lines. If I had to guess, I'd say it doesn't matter but honestly, I'm not sure.

Back to the question. I don't know why so many people think they need to change the color of the light, though I suppose it works since so many people do it. This is my guess: The cause of flowering (from light) clearly has nothing to do with blue wavelengths because phytochrome simply does not react to blue light. We are left with red light as the causal factor. Since cannabis is a short-day plant (flowering when the days become short or, long-night) and the day length is determined by duration of red light, then exclusive blue light (suggested for vegging) would cause the plant to reach the flowering stage more quickly due to a phytochrome-perceived perpetual night (is this the desired result?). But even MH should have enough red light to cause the day to be perceived and thus to postpone flowering. This is why I can't figure out why people say to use blue light. You can keep the plant from flowering by just leaving the lights on longer. The only advantage I can think of would be to give the plant more light but make it think it has a short day but that is not what they are doing.

The hormone that triggers flowering in cannabis has to build up - ANY light that triggers photosynthesis will destroy this hormone and interfere with the flowering process up until nearly the end of flowering (some clever people run their plants indoors for the first 6 weeks then finish them up outdoors in the summer sun because the hormone has built up so much that the plant cannot easily revert back into a vegetative stage.) Doesn't matter if it's blue light or red.

[GP73LPC]

wow, very technical thread !

thanks to you guys who know this stuff so the rest of us can learn :thumbsup:

[GetThisOrDie]

Ok so....

Ive read tons and tons since I started indoor growing. Ive always taken the blue light/mh/veg and red light/hps/flower comments as fact since ive read it so many places. Im now having problems finding the science behind that. I kept reading over what he was asking and I see where he is coming from. I looked at the charts on a page someone linked up above and it shows the peak absortion rates for Chloro A,B, and C. Like he said it shows the peak levels near the green and yellow. So why make these LEDs exact sectrums that are so low on the peak absortion chart?

Maybe im missing something....

Ive also read on some peoples logs that running MH or HPS the whole way makes no difference in their grows. I realize that people just typed out half a science textbook worth of info but I didnt see anywhere explaining why 400nm and 660nm are so important if they are so low on the absortion chart.

[khyberkitsune]

Ok so....

Ive read tons and tons since I started indoor growing. Ive always taken the blue light/mh/veg and red light/hps/flower comments as fact since ive read it so many places. Im now having problems finding the science behind that. I kept reading over what he was asking and I see where he is coming from. I looked at the charts on a page someone linked up above and it shows the peak absortion rates for Chloro A,B, and C. Like he said it shows the peak levels near the green and yellow. So why make these LEDs exact sectrums that are so low on the peak absortion chart?

Maybe im missing something....

Ive also read on some peoples logs that running MH or HPS the whole way makes no difference in their grows. I realize that people just typed out half a science textbook worth of info but I didnt see anywhere explaining why 400nm and 660nm are so important if they are so low on the absortion chart.

That absorption chart posted likely came from a study of Algae which have the extra side-structure that processes green light. In fact almost every one of those charts is derived from an algae study, as algae is inexpensive to produce and easy to create large quantities with a bare minimum of energy, this makes it a perfect sample test plant, but sadly, the results are useful only for under-water lighting.

Note you rarely see green plants underwater as often as you do above/on the surface of water - most seaweeds and kelps are brownish/yellow color, not green. They absorb more green, reflect more yellow and just barely use any of the sparse red/blue that manages to filter through the water.

Start taking terrestrial plants that are exposed to full sunlight, and that chart will almost universally reverse itself peak-wise.

[demoreal]

Whats up, Thepaan start some science threads. All your posts are really informative. I would rep you but I already did a while back. Seems like other people have. Every time you leave a post somewhere you get a new green dot.

[GetThisOrDie]

Thanks for the info! That would make sense... unfortunately I saw the graphs in some online cannabis grower book thing... let me try to find the link. Bahhhh..

Anyways that would make sense. So maybe the guy who started the post saw the same graphs I did??

[headshake]

i haven't read through this whole thread yet, but i'll go ahead and give my $.02. chlorophyll a peaks both at 430nm AND just slightly less at 662nm. chlorophll b at 453nm and then slightly less at 652nm. LEDs usually only push two wavelengths, the two major ones for chlorophyll aborbtion, which push ATP and NADPH. white light runs the entire spectrum. there are other wavelengths that are needed by plants, such as beta carotene, phycoerythin and phycocyanin. plants need more than two wavelengths to complete all of their business....not that it can't be done by two, obviously.

part of the problem is that unscrupulous vendors jumped on the LED bandwagon and pushed inferior products with specific wavelengths (these emitters are cheaper than white) in a rush to get their products to market. while they do work, see Str8's log, but they aren't quite there yet. once the white emitters are more common and your plants can get the entire spectrum, LEDs will kick ass.


-shake

[headshake]

also, carotenoids ABSORB blue light. this light is used in photosynthesis, and carotenoids help protect chlorophyll from photodamage.


-shake

[khyberkitsune]

phycoerythin and phycocyanin are found in aquatic plants/algae and cyanobacteria mostly. There are not many terrestrial plants with such structures - Lichens are one of the rare examples I can think of that do have these, and even then they rarely use it directly as it's contained by the bacteria which thrive with the fungus, the bacteria use it more and the fungus benefits on the side. It's a very strange symbiotic relationship the lichen has with itself.

Also, phycocyanin theoretically cannot exist within the same structure if it has a carotenoid. This is why you won't find it in most terrestrial plants, as most terrestrial plants have carotenoids, which absorb aqua light around 510nm at the highest quantum response peak and 530 at the second-highest.

[demoreal]

khyberkitsune, you rule too.

[thepaan]

First, it's great to know I'm appreciated. I did a lot of reading to learn what I think I know and I'm glad some other people can put that to good use. But this is as much for me as for you because I learn as much as I share here.


The hormone that triggers flowering in cannabis has to build up
I think it is OK to think about it this way but the truth is actually more complicated. For a short-day plant, like cannabis and rice, long-day conditions cause a hormone to be produced which delays flowering by supressing the hormone which causes it. When the long-day conditions expire the flowering hormone is no longer supressed and is free to express itself due to the diminished existence of the other hormone.

Reference (http://jxb.oxfordjournals.org/cgi/content/abstract/58/12/3091?ijkey=0901721c1f0f24c9dc16e3eb0d885553389923e 6&keytype2=tf_ipsecsha)


I don't have many references for this next bit as I usually do because I'm tired and it is late. I can find some later if anyone makes the request.


Some nonsense about absorption spectra....

I think a lot of people have huge misconceptions about what the different pigments in plants are for. Lets say there are two classes of pigments: primary pigments and accessory pigments. For land plants, the two primary pigments are chlorophyll a and b. Everything else, which includes carotenoids, xanthophylls, phycocyanin etc., serves some other function in support of the primary pigments so that they can operate at peak efficiency. For example, carotenoids can act as antenna pigments to supply the photosystem cores extra energy in low-light conditions. At the same time, carotenoids can absorb excess energy from photosystem II when it outpaces photosystem I in unbalanced or high-light conditions. You may see other pigments in an absorption spectra for a number of reasons (including, as khyberkitsune said, because they are talking about algae) but what you need to know is that they are irrelevant. For a perfect light source there is no need to stimulate anything other than chlorophylls a and b unless (and this is the only caveat) we wish to evoke a specific response. This caveat has an example in cucumbers - no one has identified a pigment in the green range but cucumbers will simply not grow without some greenish light.

I'm going to assume that any spectra you have seen are wrong. Most of the ones floating around the intaerweb are absorption in vitro (in the glass). We want action in vivo (in the living). To illustrate the difference between absorption and action I want to talk about how we get a sunburn. The UV light from the sun is absorbed by our skin and kills the cells there then we have a burn. We know that it is UV light because if it were any other light then we would be getting sunburns inside from artificial light. Our skin absorbs more than just UV light because if we reflected all light then we would be perfectly white but most people are at least a little off-white and some of us are dark as night. So we have an absorption spectra for our skin which is much broader than the action spectra which causes sunburns.

For plants we are interested in only the action spectra - that is the spectrum of light for chlorophylls a and b which cause a plant to produce oxygen (or, as it is actually measured, to consume carbon dioxide). Action spectra always show the red peak (around 660 nm) higher than the blue peak (around 450 nm). Most spectra will show the blue peak almost as high as the red peak but others will show the red peak extremely higher than the blue peak. This difference comes from the different ways which light can be measured. From our basic physics class we learned that light is both a particle and a wave. Most scientific experiments measure light by counting the particles, or number of moles. Light also has energy. The longer wavelengths (660 nm, or red) have less energy than the shorter wavelengths (450 nm, or blue). Because of this, measuring in moles tends to favor more energetic light because for the same number of particles, blue light will have significantly more energy than red light - yet action spectra still show red wavlengths to have greater effect using this measurement. If we convert this action per photon to action per unit energy then most plants in blue light alone (450 nm) are performing photosynthesis at only ~60% the rate of those same plants in red light alone (660 nm).

Proper Action Spectra (http://www.general-cathexis.com/images/ActionSpectra003.png)

This brings us back to why we are using LEDs. In order to stimulate a plant to grow most efficiently we must use deep red light (around 660-ish nm). This will allow us to use the least amount of energy in to get the maximum amount of growth out. Still, this is not quite enough. Certain other responses are only realized in other wavelengths of light. Fortunately, most of these for most plants happen to be in the blue with broad response ranges so that 10-20% of your red output added again as blue (around 450-ish nm) will be enough to take care of these. This has been found to be the minimum requirement for growing most plants and indeed applies to our favorite plant. LEDs fit the bill for specific wavelengths and given their other benefits seem the best choice for this application at the moment. But, that doesn't mean we can't minimize even further if another technology comes along (I'm still waiting for these induction lights to get more attention).

Anyway, I hope I have not bored anyone. For exactly how much light per unit area per day, look into Daily Light Integral (DLI).

[Weezard]

Aloha ThePaan


Beautiful post brah.
Mahalo!:1baa:


Weezard

[RackitMan]

Thanks for an in-depth response. :thumbsup:

While 660nm is the most efficient, it appears that 620-630nm is like 85-90% as efficient at 1/2 to 1/3 the initial cost, so as a hobbyist I will probably stick to red instead of deep red unless I am missing something.

As to the red/blue ratio, that sounds great in theory, but I have yet to see any test results of different ratios. Do you know of any actual studies? I will try to find it, but as I mentioned elsewhere, on another cannabis website, the experts (theoreticians not just growers) claimed the best blue to red was like 1.2 to 1.5 to 1 in favor of blue.

Also, my seedlings and early veg seem to do better with more blue. Is that just a misconception/expectation error?

[CovertCarpenter]

...but it seems that plants need a coupla spikes in the spectrae... for the red, around 630nm as well as 660nm, and the blue around 450nm as well as 470nm. Trying to remember where I heard it, but for flowering, apparently far red around 720nm is also needed. I'm sure that there are other bits of the spectrum that should be represented, hence most LED manuf's adding some type of white and / or 'amber' at around 610nm...

khyberkitsune and Weezard have mega-experience running and building these things, something I hope to be doing as well before too long :)

[Greenmain]

I don't have many references for this next bit as I usually do because I'm tired and it is late. I can find some later if anyone makes the request.

For a perfect light source there is no need to stimulate anything other than chlorophylls a and b unless (and this is the only caveat) we wish to evoke a specific response. This caveat has an example in cucumbers - no one has identified a pigment in the green range but cucumbers will simply not grow without some greenish light.


Many of the comercially viable led lights out there are currently going threw an evolution. That evolution is moving from 2 band(460nm and 630nm or 660nm) to 4,5,6 and even more bands of light. This is in direct contrast to your statement. Lets use the 90watt ufo just as a discussion point (even thou we all know there quiet lacking in quality). The led ufo has 5 version I am aware of they are as follows:
First Generation: 8:1 or 7:2 for Red (630nm) & Blue (470nm)
Second Generation: 8:1 or 7:2 for Red (660nm) & Blue (470nm)
Third Generation: 7:1:1 for Red (660nm)70pcs & Blue (470nm) 10pcs& Warm White (2700K)10pcs
Fourth Generation: 7:1:1 for Red (660nm) 70pcs& Blue (470nm)10pcs & Orange (610nm)10pcs
Fifth Generation: Red (660nm)40pcs & Red (630nm) 20pcs& Blue (470nm)10pcs&orange(610)10pcs & Blue (440nm)5pcs & Violet (410nm)2pcs &Infrared (740nm)3pcs

As you can see they reached "your version" of the perfect light on the second generation. Why produce 3 more versions? if they got it right on the second try? I just can't believe that 2 wavelengths of light are really all the plant needs. I need more proof.

To that end I am planing on using white leds instead of blue leds. White leds as some of you know start life as a blue led and than add phosphorous(that flores and creates the other colors you see as white).

http://www.ecse.rpi.edu/Homepages/schubert/Light-Emitting-Diodes-dot-org/chap21/F21-08%20Spectrum%20white%20P%20LED.jpg

Your thoughts? And your rebuttal in defense of 2 color light?

[Greenmain]

Now in understand that these china made lights are not the best on the market but they are far from the only example of lights being redesigned with more and more colors of light. Would you suggest that this is only for marketing reasons? Customers demand more colors so they put them there to sell lights?

(addition talk on the white led) This will give me a much broader spectrum of light. Now I will still have a large amount of 660nm light with a smaller portion of 630nm light. In addition to that I plan on a second stage for my light consisting of UVa and 605-620nm and some deep red. Most likely 30-40 worth total(4watt(uv)30watts(610nm)6-10watts(730ish) that can be switched on around flowering time.

[khyberkitsune]

"As you can see they reached "your version" of the perfect light on the second generation. Why produce 3 more versions? if they got it right on the second try?"

It's called marketing. Look at the men's razor marketing, and you will understand, most people making LED panels are following the exact same methodology. In reality, they have NO CLUE which wavelengths are the most efficient so they're just throwing out random mixes. I've seen 11-band panels, and I laugh. Quad-band with trace is all you need for terrestrial plants, and you need hex-band for aquatic plants.

"Customers demand more colors so they put them there to sell lights?"

No, the customers generally don't have a clue so they're led to believe "more is better" when the purpose of LED lighting is to target only what's needed for the most efficient growth and production.

Few makers of panels will EVER be straightforward with the customer, it's all about making the sale to them.

[Weezard]

Now in understand that these china made lights are not the best on the market but they are far from the only example of lights being redesigned with more and more colors of light. Would you suggest that this is only for marketing reasons? Customers demand more colors so they put them there to sell lights?

(addition talk on the white led) This will give me a much broader spectrum of light. Now I will still have a large amount of 660nm light with a smaller portion of 630nm light. In addition to that I plan on a second stage for my light consisting of UVa and 605-620nm and some deep red. Most likely 30-40 worth total(4watt(uv)30watts(610nm)6-10watts(730ish) that can be switched on around flowering time.

Aloha Greenmain

2 points, for enthusiasm.:thumbsup:
Love to see folks trying things for themselves.

And about multi-band lights?
There seems no need with Cannabis. 2 colors are quite adequate.

Then why hawk 5 band, new, and improved, "super" lights?
It's a crowded market, and most sheeple can be fooled most of the time.
So, if ONE blade gives a clean shave, 5 blade razors must be 5 times mo' betta' Ya?:(:D

Same marketing folks that sell us "better" eggs.
(I don't wish to know where they stuff the "extra" vitamins an' minerals so da eggs come out mo' betta.):wtf:

Any road, the fact that 2 colors will grow great bud, is the main advantage of LED growing.
Not gotta pay for generating colors that the plant does not use as efficiently.
(We pay 5X what mainlanders do for electricity.:()

So, I no gonna "blind you wit science", no can.
I dunno too much science.
But I do know good buds.:jointsmile::stoned:

A little ~460nm. a bunch of 660nm. and healthy roots will grow buds like the sun. At least fo' me it does.:cool:
Can't guarantee your milage, of course, but I could not be happier with my well focussed dichroics.:thumbsup:

Please start a multiband thread and run a side by side with a multi and dichroic. I'll be watching with great interest.

Yer welcome, brah.
Them 2 pennies was burnin' a hole in me jeans anyway.;)

Aloha Y'all
Weezard

Add: Oops, Sorry Khyber. Posted before I read your last post making the same point.:stoned:
GMTA? Seems obvious, actually.:)
W.

[khyberkitsune]

GMTA, indeed :)

I'm actually doing a dichroic right now, Weezard, 12/12 from clone, 2:1 460:660, 30w. Link is in my sig. :)

[vannewb]

Quad-band with trace is all you need for terrestrial plants, and you need hex-band for aquatic plants.
What's your currently preferred bands & ratios?

(I'm guessing from your current 2:1 experiment that you're still trying to find a better mix)

[SupraSPL]

You can use 630nm rather than 660nm and it works no problem. Actually it works better because currently 630nm are available on more efficient chips than the 660s. Once we get our hands on the new high efficiency 660s we will experiment to find the most efficient ratio of 630s:660s.

As far as blue/red ratio, it very much affects stretch. So we use more blue during veg and also the first few weeks of flowering if you are trying to control a sativa dom. Red photons are more efficient at driving photosynthesis and they require significantly less power from the emitters per photon so it is beneficial to use as much red as you can get away with while still controlling stretch.

White light can help some strains ripen on time. White LEDs also have a convenient blue peak at 440-450nm. As an earlier poster mentioned, plants use photons from all the visible wavelengths for photosynthesis, including green. I expect that the small amount of these wavelengths contributed by the white LED is used very efficiently.

Plants may go through some period of adjustment when they are suddenly presented with a light of very different wavelengths. Therefore it may be useful to provide some white even during vegging. Since the white LED provides quite a nice peak of blue, it seems possible that a simple combination of white and red could be very effective. Another bonus would be a more even spread of wavelengths reaching each leaf. I will put that theory to the test as soon as I get the new 660s.

[Weezard]

GMTA, indeed :)

I'm actually doing a dichroic right now, Weezard, 12/12 from clone, 2:1 460:660, 30w. Link is in my sig. :)

Aloha Khyber,

I'm subscribed to that thread and follow it closely.
Don't usually poke my nose in unless I have something to add or see a question that I actually KNOW the answer to.

You do jus' fine without unsolicited advice. :greenthumb:

Jus keep pokin'.:weedpoke:
Weeze

[Weezard]

Aloha, Supe


That's why I haunt this board.
Got mo' fact, and less fnord


Got choke folks like you
Tryin' stuff I no can do.


No got the resources to humor my curiosity.:(


When I started growing, it was about affordable meds.
Now, it's gone from hungry lung to voracious mind.
I jus' have to know how it all works.

The meds are now what limits my quest.
Exceeding 3 Zs per person can turn patients into inmates round here.:wtf:

So, please keep :weedpoke: it and postin' it.
The wilder, the better.
There are no "failures" 'cause it's all information.:cool:

Mahalo nui fo' da data.

Weezard