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LED red and blue spectrum / cfl concept?


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  #1  
Old 03-10-2011, 09:42 PM
CAPT38 CAPT38 is offline
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Default LED red and blue spectrum / cfl concept?

My question is this....if plants only absorb certain spectrums of light such as red and blue (blue for growth and red for bloom) why don't we just use these colors like with LEDs ?
My real question is if red and blue leds grow plants as well as what I have been reading, then why wouldn't red and blue cfls work.
A top of the line led light is in the ball park of. $2500
13 watt. Colored. cfl is $5
From what I have been reading leds have less lumens than cfls, and the reason that they work so well is by targeting the red and blue spectrum of light in theory a red and blue CFL should work as well or better than leds right?

Just curious.

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Old 03-11-2011, 12:49 AM
GpsFrontier GpsFrontier is offline
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My question is this....if plants only absorb certain spectrums of light such as red and blue (blue for growth and red for bloom) why don't we just use these colors like with LEDs ?
Actually plants absorb more than just blue and red, they actually absorb every color in the rainbow. Think of it in shades, there's a multitude of different shades of blue in the rainbow, same as with red. Orange shades are important to plants as well, but are really only different shades of red (mixing of red and green light produces shades of yellow, orange). Red and Blue are two primary colors, but depending on how they are mixed with green can make every color in the rainbow.

But it isn't actually colors that plants are absorbing, the plants are actually absorbing wavelengths of radiation (energy). The radiation/energy is what fuels the process of photosynthesis in plants. Each color of the rainbow is a different wavelength of energy, colors are just a perception by the human eye. That's why when you use a MH bulb that's in the blue spectrum, you don't actually see blue light, and it doesn't make everything look blue. The blue is the wavelength of energy given off by the bulb.

The reason that you see the blues and reds so deeply in led's is because they focus on a narrow band of this spectrum. Each LED bulb can only give off one wavelength of energy, unlike a bulb that can give off thousands of wavelengths. There was a simple experiment done on a show called "Head rush" (my the people who do Myth busters). They took 3 light tubes (glow sticks), one of each primary color (red, green, and blue), attached them to the spokes of a bicycle wheel. Then posed the question what color will you see when they spin the wheel and the colors all blur together. The actual color you see is white. It's not a coincidence that's the color you see from a MH bulb. All the colors (wavelength of energy) are mixed together. It is no coincidence that is the color of light you see given of by the sun (that contains all the colors in the rainbow perceived by the human eye), and contains each and every wavelength of energy/radiation.

Primary color - Wikipedia, the free encyclopedia (scroll down to "Biological basis")

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My real question is if red and blue leds grow plants as well as what I have been reading, then why wouldn't red and blue cfls work.
I'm not sure what it is you have been reading, but if it's what the LED light manufactures are writing, and calling it scientific data, you may want to take another look. I call that propaganda, and it's all written to try to sell products, and isn't objective information. Although there is no doubt that LED's use less electricity, I haven't seen any objective study's that suggest that LED's are even close to the capability's of MH and hps yet. I have seen that for some specific plants, and depending on the number of LED's, and how they are set up can grow some plants well. But nothing in comparison to what using MH and HPS can accomplish.

As for using Blue and Red colored cfl bulbs. As I said in answer to the first question it isn't about the color visible to the human eye ,it's about the wavelength of radiation/energy given off from the bulb. So you cant just color the bulb blue or red and expect it to work. But CFL's do come in blue and red spectrum's, but just like MH bulbs they contain all the other wavelength's also, so they look white to the human eye.

It has been a while but if I remember correctly the lower "K" numbers are the red spectrum (like 2700K), and the higher "K" like 6500K are the blue. Color and Mood : ENERGY STAR. Here they mention that the lower numbers are more yellow to the human eye, But remember that yellow is shade of red (made from red and green primary colors). So the lower the number, the more in the red spectrum the bulb is. When talking blue and red spectrum's, they are not saying that they don't contain other wavelengths (colors,) just that they focus more in one area than another.

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A top of the line led light is in the ball park of. $2500, 13 watt. Colored. Cfl is $5
As for the cfl, colored glass in a cfl bulb is only going to block the energy/radiation from reaching your plants, just the same way putting on sun glasses blocks the suns energy/radiation from reaching your eyes. As for LED's being expensive, besides the fact that it's a relatively new technology being used in hydroponics, there's a difference in the LED bulb. The LED's used for growing plants are a high output (high intensity) LED bulb, and can run as much as $5 or more for just one LED bulb. Depending on the LED light fixture, it may have 40-50 of them, to hundreds and hundreds of them. But the light intensity from even these High intensity LED's are no match whatsoever to the light intensity of MH and HPS. Besides the light intensity, LED's are very limited in the range/spectrum of energy (wavelength) they put out, and again are no match for the MH and HPS.

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From what I have been reading leds have less lumens than cfls, and the reason that they work so well is by targeting the red and blue spectrum of light in theory a red and blue cfl should work as well or better than leds right?
You can try using colored cfl's bulbs, but I can pretty well guarantee you wont have any luck. But if they do by some chance grow plants, you would still be better off using the same output bulbs, but without the colored glass. Again it isn't about the color of visible light to the human eye, it's all about the wavelength of energy/radiation given off by the bulb, and the intensity of it that reaches the plants canopy (foliage/leaves) that maters.
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Old 03-11-2011, 03:11 PM
hydrophotobio hydrophotobio is offline
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I just thought I'd drop by and say that there are some HUGE misconceptions behind LED.

Disclaimer: I do this professionally across the globe. Not just lighting, but full crop production systems that feed small countries. This includes producing certain grass crops using ZERO LIGHT at all for livestock fodder.

The majority of plants do not react along certain wavelengths, and this can be verified with a simple CO2/O2 exchangemeasurements or via protein fluorescence observations.

In fact, a majority of non-woody plants will have adverse reactions to exposure to green light, such as stunted growth or hindered reproduction. Trees, on the other hand, need green light to fulfill their full reproductive cycle properly.

Most simple vegetative crops, such as lettuces, basils, spinach, celery, do well with a mix of three or four wavelengths of light from the red and blue range. Most fruiting crops have shown similar results, like tomatoes and peppers, and strawberries.

You can get similar results by buying true primary-color T5HO bulbs, they do make pure 460nm and 630/660nm tubes but they get expensive, almost as expensive as LED, although the price of LED is dropping rapidly.

Don't be fooled by more bands = better results. That's simply unfounded. I have a tri-band 50w panel, and the same panel using quad band + 4500K white. The tri-band had the EXACT SAME PERFORMANCE as the quad-band when it came to the test crops of everbearing strawberries and spinach. I've seen dichromatic panels perform similarly.

The fact is, in the visible range, there are four wavelengths that are the most active. Trying to stimulate phycocyanin and phycoerythrin is pointless as that is primarily found in marine flora, not land flora. Just recently, a bacterium with a chlorophyll that could directly power photosynthesis with IR light (which we previously thought impossible) was discovered, but again, it's only in that bacterium - expect everyone to start unfoundedly saying "Stimulates Chlorophyll F!" with their sudden addition of IR to their panels. In fact there still isn't any real solid published Emerson Effect evidence. Ther's a bunch of conjecture and speculation, but not one single double-blind experiment conducted.

Colored CFLs aren't going to work well. You're losing light output with a filter instead of converting all possible energy into the wavelength desired, and you can't even guaranteed that colored filter is allowing the desired wavelengths through.

To address one statement made:

"But the light intensity from even these High intensity LED's are no match whatsoever to the light intensity of MH and HPS."

I'm bleaching plants from 18 inches away with a 300w panel using true 3w diodes. 2,000umol+ intensity (that's sunlight intensity) from a foot away, unlensed, smashing the outputs of a 400w CMH. If you want to go by the latest, Cree's about to drop a 200+ lux/w white diode out. Currently, we've got 150+ (but that doesn't matter, photon flux density in certain wavelengths matters.)

Also, most LED panels are using research from the 90s, and specifications from the 90s. that 7:1:1 (or similar) ratio is just GARBAGE. It's fine for vegetative plants but for producing fruits and flowers you MUST have more blue for bulk mass production, as it's the higher-energy blue photons responsible for the majority of biomass production. All that red does nothing without the right balance of blue to match!

http://i.imgur.com/j9GP1.jpg

That's a pic of me in the UK research facility. Loose Leaf lettuce, 8 days from seed, testing various ranges/combos of reds and blues.

Oh, for fun, I can also produce certain crop types without light at all (not talking white asparagus or endive, we're talking green grass for livestock.)

http://i.imgur.com/woDrp.jpg

Like that.
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Old 03-11-2011, 03:14 PM
GpsFrontier GpsFrontier is offline
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I just ran across these today, and thought it might be of interest.

Ask Erik, LED grow lights
Next Generation of LEDs: The Diodes Strike Back
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Old 03-13-2011, 03:07 AM
GpsFrontier GpsFrontier is offline
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The majority of plants do not react along certain wavelengths, and this can be verified with a simple CO2/O2 exchangemeasurements or via protein fluorescence observations.

In fact, a majority of non-woody plants will have adverse reactions to exposure to green light, such as stunted growth or hindered reproduction. Trees, on the other hand, need green light to fulfill their full reproductive cycle properly.
I would like to see the research that supports the statement that plants don't respond to wavelengths of green light. Green light is 1/3 of the full spectrum of light (wavelengths), and that would be saying plants have adverse effects to natural sunlight. That's what I would call unfounded (even without being a scientist). That's basically saying that 1/3 of the suns energy (light) is useless to plants. Beyond that you would be saying that one third of the suns light is actually harmful to plants. But in fact, plants have evolved over billions of years, and have adapted to using the suns light very well, and with absolutely no adverse reactions to being exposed to it. In fact there is nothing better for plant growth than natural sunlight (woody plants or not). So ya, I would love to see the creditable evidence that supports otherwise. Creditable meaning from independent research departments, not product manufactures or the research that's funded by them.

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Don't be fooled by more bands = better results. That's simply unfounded. I have a tri-band 50w panel, and the same panel using quad band + 4500K white. The tri-band had the EXACT SAME PERFORMANCE as the quad-band when it came to the test crops of everbearing strawberries and spinach. I've seen dichromatic panels perform similarly.
Again here I would love to see the creditable research that supports the statement that less wavelengths of light is better. To me that's what's unfounded, and sounds like a product manufactures propaganda. Nature doesn't seem to agree. Again I state "THERE IS NOTHING BETTER THAN NATURAL SUNLIGHT FOR PHOTOSYNTHESIS, AND THUS GROWING PLANTS. That's sunlight, and includes all it's wavelengths of energy (even the green spectrum), and with no adverse effects from it, just thriving growth.

I would also love to see the creditable research results of the side by side comparisons of different plant types, that supports the claims of achieving the exact same results. I'm not talking about white LED light bulbs. I'm talking about individual wavelength LED bulbs, covering all the individual wavelengths (covering the full spectrum of natural light), where as a whole will put out a white light. As well as the side by side comparisons of LED's, and high density discharge lights, and for various plant types. Without that, and from creditable sources as I mentioned, there is no legitimate comparison, and just unfounded clams (likely from product manufactures).

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I'm bleaching plants from 18 inches away with a 300w panel using true 3w diodes. 2,000umol+ intensity (that's sunlight intensity) from a foot away, unlensed, smashing the outputs of a 400w CMH. If you want to go by the latest, Cree's about to drop a 200+ lux/w white diode out. Currently, we've got 150+ (but that doesn't matter, photon flux density in certain wavelengths matters.)

Also, most LED panels are using research from the 90s, and specifications from the 90s. that 7:1:1 (or similar) ratio is just GARBAGE. It's fine for vegetative plants but for producing fruits and flowers you MUST have more blue for bulk mass production, as it's the higher-energy blue photons responsible for the majority of biomass production. All that red does nothing without the right balance of blue to match!
Sounds like this statment is right out of the pages of a product manufactures web-page. Where is the creditable research that supports this. I know that LED technology is improving, and even slowly coming down in price. But I want to see the creditable research that shows/supports the same growth rates, plant structure, overall foliage and fruiting (in both quantity and quality) is the same or better than with MH and HPS. As well as for various plants, including large plants like indeterminate varieties of peppers, tomato's, and/or large vine plants like melons, peas, cucumbers, squash etc. is the same or better using LED's than MH and HPS. As well as using the same amount of light fixtures, and with less wattage/electricity to grow them than with HID lights. Until then, LED's are still no match whatsoever to the light intensity of MH and HPS. It doesn't make them comparable when you need many expensive LED panels to do the same job as the MH and HPS, especially when you want to grow more than one or two plants. LED's run cooler so they can be placed closer to the plants, but that's also a necessity with LED's, making it necessary to have many LED panels to cover the same amount of foliage for larger grows. And if you want more light output, you cant just get a larger wattage bulb, you need a whole new expensive light fixture.

By the time you add up all the wattage from all the LED light panels needed to grow a decent amount of plants using LED's (because of the extra panels you will need for good coverage), it's not nearly as cheep as the light manufactures say. They will say a particular LED panel is equal to say a 400 watt MH bulb, but that wont be true when you go to use it as a replacement for it, and you will need more lighting to make up the difference (weather it be LED or otherwise). At least if you don't want to sacrifice growth results, don't expect that to be true. That's just a sales tactic to sell you a LED light based on cost (electricity) savings. But they wouldn't sell nearly as many if they told you you needed the much more expensive models for that kind of coverage. And again that's just comparing coverage (intensity), and not plant growth and/or health.

A watt is a watt, and it cost the same amount of money power a watt of LED's as it does to power a watt of HID. If you add it all up, there will probably be some cost savings in electricity used with LED's, even when needing multiple LED's, though that's strictly talking cost saving in total amount of electricity used here, and nothing else. That's not comparing plant growth between HID and LED's, and/or the amount of wattage needed from the LED's in order to have acceptable growth results, much less in comparing it to the growth of HID lighting. But regardless of what the manufactures say, you will need many multiple expensive LED panels to do the same job as MH and HPS lights, and/or very expensive large models. Now your grow just got way more expensive as a result. And who wants to wait ten years for the difference in electrical cost to finally make up for, and start paying off after the much higher initial cost.

P.S. Don't get me wrong, I think LED's have a place in hydroponics, and perhaps may even someday be the preferred lighting choice. But they still have a long way to go before they can match MH and HPS, regardless of what the LED manufactures try to sell you on. I'm also hoping to see the costs come down to where they would be cost effective to buy, even if only as supplemental lighting. But I'm not going to shell out $300-$400 for a light to grow a small amount of lettuce based on less electricity, when I can build a florescent lighting system to do the same job (if not better) for about $50.
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Old 03-13-2011, 03:31 AM
hydrophotobio hydrophotobio is offline
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"I would like to see the research that supports the statement that plants don't respond to wavelengths of green light."

Practically every cannabis forum out there can tell you this, along with multiple non-woody bonsai growers (myself being one.) I didn't say ALL plants, but a fair majority do not respond in any favorable fashion to green light. This applies to primarily terrestrial plants. Marine flora have far different response ranges and also additional helper chloroplasts.

"That's basically saying that 1/3 of the suns energy (light) is useless to plants."

Plants only use about 5% of any energy they're irradiated with at any given time. The conversion from photons to energy is highly inefficient to boot. The truth is a HUGE majority of light is practically useless, as the plant simply can't use it because it's already fully charged - think of chlorophyll as capacitors/batteries with built-in converters. In any energy system, you take in too much energy, you risk burning out. Chlorophyll does this constantly in natural sunlight. It degrades due to such high energy irradiation. That which does not get used (primarily green) is either reflected back to us or just generates heat off the surface of the plant tissues, the latter effect being goverend by thermodynamics.

"Again here I would love to see the creditable research that supports the statement that less wavelengths of light is better."

Read any number of research that uses a control light source and then supplements with monochromatic sources. I believe you'll find the ones performed on wheat, barley grass, and wheatgrass to be quite informative due to easy repetition of the experiments and easy creation of double-blind testing across huge swaths of crops.

In fact, I simply grow fodder grass using practically zero light (quantum meter effectively reads zero,) and it's as healthy as typical grown fodder grasses with about half of the root hormone content that upsets multiple ruminants. In multiple crops, less is far superior, depending upon purpose. You're limiting yourself to inside the box thinking.

"I would also love to see the creditable research results of the side by side comparisons of different plant types, that supports the claims of achieving the exact same results. I'm not talking about white LED light bulbs. I'm talking about individual wavelength LED bulbs, covering all the individual wavelengths (covering the full spectrum of natural light), where as a whole will put out a white light."

Thousands upon thousands on Springerlink, Wiley Acience Archive, and independent research done by everyone from home gardeners to University professors like John Lydon, all acros the web. You should be quite able to find them, just start by picking your crop. I'd recommend Dutch sources as they tend to be a bit more detailed, especially concerning yields in terms of yield per kilowatt-hour and nutritional content, much moreso than most US-based scientists. They also have better hydroponics systems overall.

"Sounds like this statment is right out of the pages of a product manufactures web-page. Where is the creditable research that supports this. I know that LED technology is improving, and even slowly coming down in price. But I want to see the creditable research that shows/supports the same growth rates, plant structure, overall foliage and fruiting (in both quantity and quality) is the same or better than with MH and HPS. As well as for various plants, including large plants like indeterminate varieties of peppers, tomato's, and/or large vine plants like melons, peas, cucumbers, squash etc. is the same or better using LED's than MH and HPS."

I've done it across various other forums, I'll be more than happy to do it here. In fact, doing it across forums is what got me my research director position in the first place.

So sit back, enjoy the show. Wait for me to get my seeds.

BTW, remember that lettuce picture in my post above? That was eight days. The crop typically takes seven weeks under natural sunlight in an NFT system.

http://i.imgur.com/MCRg8.jpg

Done in twenty-eight days. We're waiting for nutritional analysis to be able to make final judgments against sunlit greenhouse lettuce of the same seed stock batch, but the weight is perfect for market and the color is excellent.

Sorry I can't give you day-by-day from our research facilities but that's absolutely not allowed by my NDA.

Nothing in my NDA prevents me from doing the same thing at home and showing it off, so here I am.
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Old 03-13-2011, 07:10 AM
GpsFrontier GpsFrontier is offline
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Practically every cannabis forum out there can tell you this, along with multiple non-woody bonsai growers (myself being one.)
Some people might, but I don't consider a cannabis forum, or bonsai growers to be creditable sources for information. Nor do I consider any forum and/or such to be a creditable source of information. Perhaps my standards of what is creditable, and what isn't, is different than most peoples. But I'm not willing to just believe what does not make scene, even when many people may be repeating it. Not without my standards of creditable research to support it.

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Plants only use about 5% of any energy they're irradiated with at any given time. The conversion from photons to energy is highly inefficient to boot. The truth is a HUGE majority of light is practically useless, as the plant simply can't use it because it's already fully charged - think of chlorophyll as capacitors/batteries with built-in converters. In any energy system, you take in too much energy, you risk burning out. Chlorophyll does this constantly in natural sunlight. It degrades due to such high energy irradiation. That which does not get used (primarily green) is either reflected back to us or just generates heat off the surface of the plant tissues, the latter effect being goverend by thermodynamics.
This is interesting, but again I haven't seen anything to support the theory as of yet.

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Read any number of research that uses a control light source and then supplements with monochromatic sources. I believe you'll find the ones performed on wheat, barley grass, and wheatgrass to be quite informative due to easy repetition of the experiments and easy creation of double-blind testing across huge swaths of crops.
There is very little creditable information that I have found in my searches thought the past few years about using LED' lighting for plant growth, and/or the subsequent wavelengths of light related to plant growth (LED or otherwise). But non of what I have found supports the theory that very few wavelengths (spectrum's) of light are needed by the plant. In fact just about everything I have read suggests the opposite. And along with a wide spectrum of light (wavelengths), the intensity of the light are the two most important factors in artificial lighting and plant growth. Without any creditable information to the contrary, I have no reason to believe otherwise.

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Thousands upon thousands on Springerlink, Wiley Acience Archive, and independent research done by everyone from home gardeners to University professors like John Lydon, all acros the web. You should be quite able to find them, just start by picking your crop. I'd recommend Dutch sources as they tend to be a bit more detailed, especially concerning yields in terms of yield per kilowatt-hour and nutritional content, much moreso than most US-based scientists. They also have better hydroponics systems overall.
I'm not interested in study's done by home gardeners, again that's not what I consider to be creditable (interesting but simply not creditable). However I am interested in University study's, and that's what I focus my searches on, as well as have been looking for these past few years. And I simply haven't found thousands of study's related to plant growth and artificial lighting as you suggest exist. I haven't herd the name so I just did a quick search for John Lydon and all that came up was some forums and nothing useful in the top ten anyway (and again not my standard of creditable).

I like seeing pictures, but pictures are not what I consider creditable documentation and/or a complete study, nor does that show comparisons. For instance you mention comparing days of artificial light and natural sunlight, but there are a whole lot of variables that will affect the results. That's what a creditable study would be looking at and comparing in their experiments. That's also what makes the difference between a creditable study, and a home gardeners version of a study. No offense, but I don't just look at a picture that someone posts in a forum and consider it creditable information. Without the particulars of a controlled and well documented experiment, and including a control of each variable to base the results against, it's simply just a picture of a plant. And thus nothing to suggest the creditable information I have seen is incorrect. But it's always nice to see what other people are doing, and how they are doing it.
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Old 03-13-2011, 01:54 PM
hydrophotobio hydrophotobio is offline
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"I'm not interested in study's done by home gardeners, again that's not what I consider to be creditable (interesting but simply not creditable). However I am interested in University study's, and that's what I focus my searches on, as well as have been looking for these past few years. And I simply haven't found thousands of study's related to plant growth and artificial lighting as you suggest exist. I haven't herd the name so I just did a quick search for John Lydon and all that came up was some forums and nothing useful in the top ten anyway (and again not my standard of creditable)."

I don't even think you're looking. Look what took me less than twenty seconds of ARS searching:

http://www.ars.usda.gov/pandp/people...?personid=3481

Don't rely upon Google for information as it's been totally re-geared towards advertising, not information and facts. Use official government and university searches from now on and you'll likely not encounter this issue any longer.

Also, if one relies upon purely university and gov't studies to make a determination of credibility of information, and you don't perform those exact same experiments yourself to judge their validity and publish your own results, one isn't in a position to judge what is or is not credible, at all.

In my research shed, everything is tightly controlled. 1/8 acre building costs well over 10 million to build with environmental controls, lighting controls, independent raw nutrient dosage and measuring, HEPA filtration, and much, much more equipment.

We rent our facility out to scientists and companies looking to perform experiments, that's how well-controlled we can keep it, up to one tenth of a degree celscius for temperature controls, and +/-10 PPM for nutritional control on any raw nutrient. We can even control individual air flow per channel, per tier, per stacked system, adjust voltages to lights, driving current to lights, etc.
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Old 03-13-2011, 09:11 PM
GpsFrontier GpsFrontier is offline
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If I'm not mistaken you said that the study's would be all over the internet, if so some surly should come up using search engines. But thanks for the link, however I don't see any actual published study's. I see a list of 156 titles, and after clicking on more than 10 of them, each only state an objective and an a approach. All they seem to be is a list of funding requests, outlining what they want to accomplish and how they plan to go about it. But no actual study's.

Yahoo (as I usually use), Google and Bing etc. don't publish the information, they just supply links to the information on the web, and use the advanced search to narrow searches to .edu possibly .gov websites. As well as use quotation marks around specific words and phrases, and the plus sign to include specific words in the phrase to narrow down the results.

Anybody can get a .com and now even a .org website, and can publish anything they want regardless of validity. I prefer to use sites that have a much higher probability of having accurate information. Websites that anyone can get, and post anything they want like .com and .org, just don't have nearly as high of a probability of being accurate. That's not to say that a .com website wont have creditable information, but it's unwise to just assume so. And before deeming anything from any .com and/or .org website creditable, I would also need to research the website, the source the website got the information from, the background of the person that wrote it, and make sure it wasn't altered by the website before publishing it.

Even though .edu and .gov website information can still be flawed (as with any information anywhere can be) , especially if it's dated. You cant just post anything you want. The agency's and educational institutions don't post things from unknown people, they post things from people who work for them, and/or colleagues they closely work with. Therefor they have already checked into their backgrounds and are satisfying with their credentials before posting anything from them.

It would be nice if there was a collective university and/or gov database, however if there is I'm unaware of it. I am aware of many government and university sites such as:

Cooperative Extension System Offices
U.S. Department of Agriculture Home Page
Bradford County Extension Office – Solutions for Your Life - UF Institute of Food and Agricultural Sciences
Clemson University
School of Natural Resources & Agricultural Sciences | Home
Montana State University Extension - Bozeman Montana
College of Agriculture and Life Sciences
North Carolina Cooperative Extension: Home
UNL | Extension Horticulture
Introduction - General - Information - Ohio State University Hydroponic Crop Program
Small Farms / Alternative Enterprises - Institute of Food and Agricultural Sciences Extension
EDIS - Electronic Data Information Source - UF/IFAS Extension
The Alabama Cooperative Extension System
Protected Agriculture Greenhouse Project

And that's just a short list of what I already have bookmarked. Searching the sites individual is not really productive in my experience. I usually just come up with either a long list of vaguely relevant results, or nothing at all. And unless you know the exact title of of what you are looking for, that's what just what winds up happening 80%-90% of the time (even when the spelling is correct). You need the spelling to be correct, or you get nothing at all. Unlike a search engine, where if the spelling is incorrect, it gives you alternatives. And the fact is, I'm terrible at spelling.

They don't have an advanced search (that I know of) but they do usually show the url of the original document before you click on it. And I often also use pdf search engins like these to search specifically for pdf. files. I really like pdf's because I can easily save them to my computer, as well as organize them on my computer to find them easier. I also like to print them out (I find things easier to read through that way).

Free PDF Search Engine
GreatPDF - The great PDF document and ebook search engine.
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Also, if one relies upon purely university and government studies to make a determination of credibility of information, and you don't perform those exact same experiments yourself to judge their validity and publish your own results, one isn't in a position to judge what is or is not credible, at all.
So then what's the point of even looking for and reading any research? Simply saying that nothing is accurate (regardless of where it's published) unless you run experiments to verify the results is extremely impracticable. I have read that gorge Washington crossed the Delaware, but I don't have a time machine to go back in time to verify that he actually did, so I guess that bit if information cant be trusted. Sorry but I don't have millions of dollars to redo all the study's that have already been done, just to corroborate their results.

The best I can do (and try my best to do), is find multiple study's from as creditable of sources that I can find, and compare their results with each other. Even if I published my own results, that wouldn't make my findings creditable, nor does it make anyone's else. There are hundreds of thousands of books published in hard copy every year that have no validation, and there are many more websites on the internet that do the same. But each person that publishes it feels their information is creditable. And determining something creditable doesn't involve just agreeing with it.

I know that you keep referring to your facility, and their experiments, as well as the research as if that's supposed to impress me. No offense, but your just a stranger to me, just another person posting in a forum. There are lots of people that say a lot of things, and it isn't hard to find pictures online, copy them, and post theme in a forum or website, then clam anything about them they want. That wouldn't even be original. You may just believe what anyone says in a forum, and consider it creditable (as you mentioned I should do before), but I on the other hand am more realistic.

If your research facility is top secret, as well as all the experiments and research it conducts. Well then it's useless to me, and not validation of anything. Nor can I deemed any of what you say the results of it are, as creditable now can I. It just isn't realistic to deem research that cant be verified as creditable, and deem research that can be verified as not creditable. It just winds up being the say so of a stranger in a forum. All I can do with it is just keep it in mind, and maybe someday I will run across a creditable source of information that gives it some validation. Unfortunately that's the reality. And going by your earlier statement, sense I don't have the money to conduct my own study's to verify your so called research facility's results (even if they were published), so therefor I wouldn't be "in a position to judge what is or is not credible, at all," now am I. So if something can only be creditable if you conducted an experiment to validate the results, I guess it would still be useless information to me, wouldn't it. Or is there a double standard here.
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Old 03-16-2011, 01:44 PM
hydrophotobio hydrophotobio is offline
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I see the point you're making. I can agree with part of it. My facility isn't to impress you, and I apologize for unconsciously impressing that upon you, it's to show you that I'm simply not joking around, I'm a serious person and I take every thing I do very seriously. I do whatever I can to maintain any required controls, while monitoring the allowed variables.

As to credibility, well, I'm just going to have to build it up. As you said, I'm a stranger posting on a forum. In time, I hope that you'll lend me some credibility. In fact, I'm going to redo my personal setup. Pull that 120w and 90w down, and run four 50w panels - two are tri-band of my specification, two are quad-band plus 4500K of my specification, which will be told at the true start of the experiment. I'll set them up so they each get a side, and I'll separate them with light curtains so they get no effective spill-over. Everything else should essentially remain the same, as they are in the same 'room,' breathing the same air, receiving the same nutrients out of the same reservoir, they will have the same light exposure time, and they should remain in very similar ambient temperature and relative humidity. The only real difference will be the lighting used, and possibly germination time of the seeds.

Sound good to you? Anything you'd add?

Last edited by hydrophotobio; 03-16-2011 at 02:03 PM. Reason: Needed to add more detail
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Old 03-16-2011, 06:18 PM
GpsFrontier GpsFrontier is offline
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Hello hydrophotobio,

That sounds like a good setup for comparison. I know you said that the experiment is on your own dime, and so cost is probably a issue. But for me, I'm especially interested in how the LED lights compare to HID, as well as florescent (especially on the lettuce that I believe you said was planed). Also if you could use a Kill-a-watt meter to accurately record energy consumption, as well as cost to grow the plants, that would be beneficial information (especially if comparing to HID and florescent). The kill-a-watt meters come in all kinds of price ranges and with different bells and whistles. But they all will record energy consumption, and calculate cost when you input price per kilowatt that's on your electric bill, and I have seen some at Home Depot/Lowe's for under $20.
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Old 03-16-2011, 07:27 PM
hydrophotobio hydrophotobio is offline
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Got a kill-a-watt, but that's hooked up to the computer to monitor power usage. I can buy a couple more to monitor the lights on each side.

I'll need to pick up a 100w HPS system. Keep everything as controlled and even as possible.

As to the CFL question originally posted, I played around with some single-phosphor T5HO bulbs a long time ago. The red had a dominant peak of approximately 620nm, the blue had a dominant peak around 470nm, with wide swaths out in either direction from the peak due to the nature of phosphors not being as monochromatically tunable as direct LED. The bulbs were expensive, on the order of 45 dollars a tube in bulk cases of 12 tubes. I had good results with them when used with small crops, but not good enough to justify the price. Great for experimentation, just not enough photon flux density to get the job done very well. I might have had better luck if I had used a different ballast and pushed 80w through them instead of their typical 54w, but I was not about to buy an IceCap just for something I had no intention of recording, it was just for my own personal pleasure. However, if that kind of thing suits you, feel free to try it! Everything makes for a wonderful learning experience, and even failures are successes in terms of data gathered.
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Old 03-17-2011, 03:52 AM
GpsFrontier GpsFrontier is offline
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I grow everything outside in natural sunlight myself. Although That doesn't work well for lettuce here from mid-late April on, they just tend to bolt. So I'm considering growing some inside this summer. There is no way I can justify spending hundreds of dollars for LED, or MH and cooling fans. If I can find enough space to place the setup (probably the laundry room/pantry), I might be able to setup a couple of 8 plant water culture setups that I have done outside. For Lighting I'm looking at using a couple two tube T8 fixtures (possibly three), and making my own reflectors. I figure I could put together the T8 lighting for around $60. I'll definitely want a Kill-a-watt meter to be able to tell exactly how much it costs to grow the lettuce, also how much each T8 fixture cost me to run etc..
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Old 03-17-2011, 04:20 AM
hydrophotobio hydrophotobio is offline
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Lettuce bolts like mad in the summer. I've seen NFT setups using proper nutrition and mass CO2 under sunlight produce lettuces the size of my torso, but that was a highly tuned nutrient solution and 1200+ppm CO2 at all times.

I had my guys give me a measurement of my current 1w LED bars used for growing lettuce. 138 umol m^2 s-1 from 300mm away. If you could get a quantum flux reading of whatever lights you ultimately use indoors, I'd like to know, especially if fluorescent, as my bars are of equal wattage to a typical T8 at 32w.
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Old 03-18-2011, 03:54 AM
GpsFrontier GpsFrontier is offline
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It wont be that soon when I get around to putting together the indoor system. I just have too many things that need money, and not enough of it. All I really need is the lights (and a space to put it), but again that takes money. Though I have been pricing things for when I have it. I'm not sure what a "quantum flux reading" is, but would be happy to share any information I can.

Right now I'm waiting for six mini sweet peppers sprouts to get big enough to transplant into a system that I'll be reusing. But like everything else, I'll be growing them outside. Right now their in a small makeshift system (a wip-cream container with coco chips that I hand water with nutrient solution), and just getting their second pair of leaves.
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Old 03-18-2011, 02:44 PM
ProZachJ ProZachJ is offline
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I've done a bunch of LED growing with both cheap ebay LEDs and very expensive retail LEDs. I have found the main struggle with them is the trade off of light proximity to the plants and coverage area. They are plenty powerful when you can put them 6" above your plants, but that doesn't provide much coverage. For a 4x4 growing space about 360W (4) ebay UFOs seems to be enough to grow all but the most light hungry plants all the way up to cherry and grape tomatoes. I am currently doing a 4 pepper plant grow each under a 45W panel. Since each plant has its own panel I am able to keep them very close to the canopy. I am finding that this amount of light is just at the lower limit of what they need to produce peppers. Compared to my 4ft 205W T5 HO LEDs tend to grow bushier plants that flower earlier. An added benefit is the reduction of heat and all the expense that goes with trying to deal with it.
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Old 03-18-2011, 05:08 PM
hydrophotobio hydrophotobio is offline
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Gps, thank you for encouraging me to get off my butt to get some equipment.

My 50w panels draw around 47w according to the fresh Kill-a-watt I got just for the lights.

I have a 90w panel from a while ago, it only drew 60w on the meter. I thought the meter was faulty. I tried a 60w incandescent bulb, pulled 62w. I tried my 54w T5HO 4ft single tube, let it warm up, got 51-52w steady after five minutes. I thought that a driver had gone bad in the panel. I popped the panel open since it was way out of warranty, checked each driver on both strings of LEDs in the 90w. Nope, not bad drivers, the drivers are just 30w drivers.

Anybody else experiencing this with their stuff? I hope this is just some past fluke since my 50w panels are far newer than the 90w and they are pulling their rated power for the most part. I know if I pay for 90w and am told 90w on power consumption, I expect that full 90w within a few percent, no more or less, especially since I clearly specified no pulse-width modulation in my equipment when I bought it for research purposes.

I'm tempted to order a higher powered panel and see what it registers.
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Old 03-18-2011, 05:59 PM
ProZachJ ProZachJ is offline
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LEDs will almost always draw less power than their name implys. This is because they arrive at the name by counting the number of diodes and multiplying by their individual wattage. For example a 90W UFO has 90 1W diodes. The thing is if you drive a 1W diode to actually use 1W of electricity it loses efficiency vs driving it to use .5 or .75W. Basically, with LEDs it's more efficient to have more diodes and push them less hard than to push all the diodes to their max. My 345W Penetrator from Hydro Grow LED only uses 270W but has 345 1W diodes. It all comes down to the fact that we should really rate lights by the amount of Photo-synthetically Active Radiation (PAR) they emit and not wattage or lumens.

Last edited by ProZachJ; 03-18-2011 at 06:02 PM.
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Old 03-18-2011, 08:09 PM
hydrophotobio hydrophotobio is offline
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It really comes down to photon flux ensity. PAR is barely a piece of the entire equation.

Simply put, you may gain efficnency, but you lose overall photon output.

Were this the case, my 50w panels should be something like 30w, not the 47w they're pulling (just BARELY under 1w per diode, fan included.) The 50w is pushing almost the same photon flux density as the 90w at 60w, just BARELY under it. In theory, the 50w should perform very similar to the 90w.
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Old 03-18-2011, 10:21 PM
ProZachJ ProZachJ is offline
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I agree with you on losing overall output when trying to gain efficiency. Its a trade off choice that every LED manufacturer has to make. When driving the diode harder you have to ask yourself how much am I willing to do for 10% or 5% more light while using 20% more energy. The harder you push the less you get in return. They may make different choices for different lights within their own product offering because of available/cheap parts. I would bet that often times they end up making poor choices that don't really make sense.

As far as for plants though I disagree that PAR isn't the whole story. It doesn't matter how many photons you put out if they aren't at a wavelength that plants cannot utilize for photosynthesis. To compare two light directly for effectiveness on plants you woud use a quantumn light meter to measue the Photosynthetic Photon Flux Den- sity (PPFD) which according the meters manufacturer is a measure of PAR light, and boy do I need to buy one :-)


Last edited by ProZachJ; 03-18-2011 at 10:27 PM.
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