STAY AWAY FROM LED's!!!!!

MrVanker said:

Correct me if I'm wrong virulient, but it sounds like you're talking about a straight up comparison of HIDs to LEDs. I'm not 100% sure how much of your post is directed at me, but I am trying to talk about usable light, and figure out how much usable light it is possible to get from LEDs, and then it can be compared to HIDs.

Google is by no means foreign to me, I use it a lot when I post in forums. According to this PAR spectrum chart, which shows the correlation between absorption and photosynthesis rate, the absorption starts somewhere in the 300nm range (UV) and drops off just after 700nm. According to this light spectrum chart, the visible light spectrum starts at 380nm and stops at 740nm. So it would seem that as far as we know, all/most PAR light falls in the visible spectrum. In which case, how can lumens be disregarded? I'm not challenging, I'm actually asking.

PAR Chart Source
Visible Light Spectrum Source

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Wasn't really directed at anyone in particular, just the people who are mis-informed, or who don't do the proper legwork to understand the topic at hand. Your links are just links to 2 websites that would take days to read, so I'm not sure what, in particular you're looking at. However, I'm not discounting lumens totally, just the people who are comparing the HID lumen output vs LED lumen output, instead of measuring the amount of USABLE light, in lumens. The latter would be a worthy discussion, the former, no so much. LED's pump out more usable light, but not as intense as HID. This is one of the main reasons comparing them is difficult.

So the question, on this particular topic, would be how many lumens would an LED need to push to equate an HID's effectiveness in usable light? And, if you can come up with the answer to that one, the next question would be penetration. Considering you get an HID and an LED, the LED pushing less lumens, but possibly MORE usable light.......but what about penetration? All of these topics can spark intriguing conversations. My post was not directed at you, but aimed at people saying "LED light A pushes X amount of lumens and HID light B pushes Z amount of lumens, and Z > X therefore HID > LED". <---That is what I am trying to avoid.

Nice post CG!!! #5 might get you some hijacking, but I can't say I disagree with it!

Corbat420 said:

PAR Lighting has nothing to do with plants, that was a point i made 2-3 Pages ago. PAR refers to the total energy given off by a light source.

Plant Light is measured in Plant Lumens, which are the Lumens produced in the spectrum of light between 340 NM and 720 NM. LED technology has teh ability to put out up-to 80% Usable light, where a HID Light puts out around 20% Usable light, when measured in PAR. but measured in Lumens plants can use up-to 90% of LED Lighting and 50% of HID Lighting.

if LED Companies started to measure Light in Usable Lumens it would be MUCH better than confusing so many people using the PAR Measurement.

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PAR is the amount of light available for photosynthesis. To say it has nothing to do with plants is preposterous. There may be a more accurate, or less confusing, unit of measurement we could use instead of PAR, I don't know. But the simple definition of PAR directly contradicts your post.

Corbat, I think we may be talking two different kinds of PAR. I'm talking about Photosynthetic Absorption Rate. It's a measure of what spectrums of light are most absorbed and used by plants. I think that the PAR you are talking about may be related, or similar, but not the same. The photosynthesis carried out by Chlorophyll A requires two electrons to be passed to a receptor in order for the process to proceed. Perhaps that is related to the electron part at the end of your quote.

V (mind if I call you that?), that is what I was trying to get at as well, lumens of usable light. I posted those charts for two reasons:
1. In response to El Superbeasto saying that plants cannot see lumens. According to those charts, the majority of usable light falls within the visible light spectrum, which means that they can be measured in lumens and be used by the plants.
2. Just to try and spread some info. I linked those two sites, just to cite my sources for the charts. I feel that those sites can be reasonably trusted for the info.

MrVanker said:

Corbat, I think we may be talking two different kinds of PAR. I'm talking about Photosynthetic Absorption Rate. It's a measure of what spectrums of light are most absorbed and used by plants. I think that the PAR you are talking about may be related, or similar, but not the same. The photosynthesis carried out by Chlorophyll A requires two electrons to be passed to a receptor in order for the process to proceed. Perhaps that is related to the electron part at the end of your quote.

V (mind if I call you that?), that is what I was trying to get at as well, lumens of usable light. I posted those charts for two reasons:
1. In response to El Superbeasto saying that plants cannot see lumens. According to those charts, the majority of usable light falls within the visible light spectrum, which means that they can be measured in lumens and be used by the plants.
2. Just to try and spread some info. I linked those two sites, just to cite my sources for the charts.

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Ah I see I missed that first post. V works with me! The PAR acronym stands for Photosythetically Active Radiation, although your definition was accurate enough.

Corbat is attempting to discuss Plant Growth Lumens (PGL), which you can still find some people using if you can find some old posts about the switch to CFL's in horticulture. What he doesn't know is it is practically the same thing as PAR.

https://growguide.opengrow.com/CFL_Lighting_101 <--This kid attempts to explain it.....its tough to read. He cites "Human Lumens" a few times...


The problem with lumens is, by definition, a lumen is the amount of VISIBLE light. However, studies have shown plants respond most efficiently to light that could be beyond what humans can perceive. Therefore we use PAR.

virulient said:

PAR is the amount of light available for photosynthesis. To say it has nothing to do with plants is preposterous. There may be a more accurate, or less confusing, unit of measurement we could use instead of PAR, I don't know. But the simple definition of PAR directly contradicts your post.

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PAR is NOT the measurement of light available for photosynthesis. it is a measurement used in Physics to explain the amount of energy given off by a light source. TOTAL energy output of the light and an available measurement of Light Intensity. <-- THIS is the PAR Used in LED Lighting, Light intensity measurement.

this is the reason it is so confusing to SO many LED Users. they are not measuring Photosynthetic Absorption Rate, they are measuring the Photon energy, which is only one small factor in photosynthesis.

we know that for photosynthesis to take place there must be 2 electrons present, thus there must be 2 Photon's present. when only 1/2 of the Equation is taken into account the numbers are completely strewn.

Edit: Do this. Google Light intensity and Par. see if you can actually come up with a good definition. i know my science from taking basic college level Physics....

Okay, then I am still a bit confused... what do you say about most of the PAR light falling within the visible light range? That PAR chart shows the spectrum from 400nm to just past 700nm, which is the visible light spectrum. On the far left, below 400nm you get into UV light, below UV you get into Gamma radiation and X-Rays. You can infer by the direction of the line on the 400nm end, that it probably drops to 0% absorption in the 350-380nm (upper UV) range. I'm not trying to argue, just trying to wrap my head around this. I love bio, but this is more like physics! lol

EDIT: Corbat
Okay, so you are saying that when a person shops for an LED panel and sees PAR, they think Photosynthetic Active Radiation, but the company is talking about light intensity PAR?

Everything is physics.

Physics Is chemistry IS Biology. if you want to TRULY know Biology you have to know Physics and Chemistry first.

Marijuana specificly uses light as low as the 320 NM Mark. it is not absorbed by the Chlorophyll tho, it is used in the later stages of flowering to break down the chemical predecessors to THC. thats why UV/B Light is used during flowering.
Marijuana also uses Light as high as the 700 NM Mark but light between the spectrum of 380 NM and 680 NM are absorbed by the chlorophyll in the process we know as photosynthesis.
The MAIN Light spectrum Marijuana uses are the 420-460 NM and the 620-680

Chlorophyll A and B are responsible for up to 95% of the total energy absorption, Chlorophyll A is responsible for the absorption of the Red (620-680 NM) and Chlorophyll B Is responsible for the absorbtion of Blue (420-460 NM) Chlorophyll C and D are responsible for the absorption of Green Light (500-600 NM) and IR light. which is my it is impractical to run a Green or IR light.

If we were to measure in Par it would have to be Par/Sqm. this would give us an accurate reading of TRUE Light intensity. Plant Lumens (or Photosynthetic absorption rate) is a better measurement as it allows us to know the coverage of a single light.

Corbat420 said:

PAR is NOT the measurement of light available for photosynthesis. it is a measurement used in Physics to explain the amount of energy given off by a light source. TOTAL energy output of the light and an available measurement of Light Intensity. <-- THIS is the PAR Used in LED Lighting, Light intensity measurement.

this is the reason it is so confusing to SO many LED Users. they are not measuring Photosynthetic Absorption Rate, they are measuring the Photon energy, which is only one small factor in photosynthesis.

we know that for photosynthesis to take place there must be 2 electrons present, thus there must be 2 Photon's present. when only 1/2 of the Equation is taken into account the numbers are completely strewn.

Edit: Do this. Google Light intensity and Par. see if you can actually come up with a good definition. i know my science from taking basic college level Physics....

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I cannot explain it better than this, so I will simply give you this link and hope you have the free time to read it. It will clear up any confusion for you, keep in mind the difference between Photosynthetic Absorption Rate and the measurement of Photosynthetically Active Radiation. We are talking about the latter here..

http://www.keithmccree.net/Biographical/BioProf/PAR.html

Keith McCree concludes, and I'm quoting "In the applied plant sciences such as plant ecology and agronomy, there is a need for a simple system for measuring the light which is active in plant growth, analogous to the photometric system for measuring the light which is useful to humans in their daily life. The best likely candidate is "photosynthetically active radiation" (PAR)."

Throughout his career he didn't deviate. But you have taken "basic college courses in physics" so you probably know best. Who is Keith McCree anyway.....LOL.

This post just got ruined by another community college student. I'm unsubscribed.....good luck talking to that brick wall named Corbat.

I'm gonna go

And physics is based on math... I understand that. However, I am perfectly comfortable knowing that most of the foundations for what we are discussing have, for the most part, been laid for us. That's not to say that new innovations or discoveries won't be made (Neutrinos anyone?), but I think we're good.

Pretty much most of what you said, is what I have been reading. The only thing that I am still confused about (and have been for a page or two now) is the Par measurement you are talking about. I cannot find any unit of measure for light called a Par. Anywhere. I found one called peak-to-average ratio, but that applies to electrical waveforms, vibrations, radio and audio frequencies, and lastly: snoring. Also, Photosynthetic Absorption Rate is (as I understand it) the defined spectrum that the average plant uses, not a unit of measure... it's pretty much exactly what you wrote in the middle of your post.

not a unit of measure... it's pretty much exactly what you wrote in the middle of your post.

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thats JSUT the problem. you said it your self. PAR is NOT a unit of measure.

we NEED a unit of Measure. thats what i have been saying the whole time. we cant just say the light produces _____ PAR because thats the same as saying it prodeces ____ NM of light.

thats all well and fine, but if we only have enough light to sustain Phytoplankton then we arn't growing pot with it.

we need to know it produces ____PAR at ____ Intensity.

MrVanker said:

And physics is based on math... I understand that. However, I am perfectly comfortable knowing that most of the foundations for what we are discussing have, for the most part, been laid for us. That's not to say that new innovations or discoveries won't be made (Neutrinos anyone?), but I think we're good.

Pretty much most of what you said, is what I have been reading. The only thing that I am still confused about (and have been for a page or two now) is the Par measurement you are talking about. I cannot find any unit of measure for light called a Par. Anywhere. I found one called peak-to-average ratio, but that applies to electrical waveforms, vibrations, radio and audio frequencies, and lastly: snoring. Also, Photosynthetic Absorption Rate is (as I understand it) the defined spectrum that the average plant uses, not a unit of measure... it's pretty much exactly what you wrote in the middle of your post.

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You can't find ANYWHERE PAR is a unit of measurement.

As an example of the application of these principles to the practical measurement of light in plant ecology, I shall consider the measurement of "photosynthetically active radiation" (PAR).
^^Same link as my previous post

You STILL can't find it anywhere?

virulient said:

You can't find ANYWHERE PAR is a unit of measurement.

As an example of the application of these principles to the practical measurement of light in plant ecology, I shall consider the measurement of "photosynthetically active radiation" (PAR).
^^Same link as my previous post

You STILL can't find it anywhere?

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That link was to a study in the 70s (?) Debating whether PAR should be used or not. it wasn;t saying this is what PAR is going to be from now on...... it seems it wasn't picked up since no one can find it anywhere....... and we still measure light in Lumens and Lux.

the "Science" precented there can not be followed. AT ALL. i tried looking for most of teh papers sited at the bottom and cant find any of them......

That's your argument. The paper is dated? Nothing in that paper is false and nothing significant is missing. And we actually don't measure LED horticulture lights in lumens, we measure them in PAR. We measure them using PAR, as described and explained in that article. You know the article from 1973. The one that's still accurate.

Corbat
I don't think that I was ever arguing that PAR was a unit of measure. All the knowledge I have on the subject is from yesterday and today, from Google, and this thread. I found a graph which showed what spectrums of light the average plant needs and uses. So, making an educated guess, I assumed that you could measure that light in a standard unit such as lumens, which is apparently not true. So to me, the next logical step is to figure out how that light IS measured, which leads me to V's post.

V
I hadn't seen your post until after I posted that. I am reading the page through a couple times to make sure I understand it as best I can.

You can find more here McCree, Keith J. (1981). "Photosynthetically active radiation". In: Encyclopedia of Plant Physiology, vol. 12A. Springer-Verlag, Berlin, pp. 41-55.

Notice the name of the book.
You might have to track down the actual book for a copy of the article in it. Nonetheless, suggesting that KeithMcCree's studies are inaccurate is just as preposterous as saying that PAR has NOTHING to do with plants.

Conclusions
(1) In basic photobiological research, the spectral properties of both the irradiating source and the target should always be determined. These are difficult measurements, which should not be attempted without some competent technical help.
(2) In the applied plant sciences such as plant ecology and agronomy, there is a need for a simple system for measuring the light which is active in plant growth, analogous to the photometric system for measuring the light which is useful to humans in their daily life. The best likely candidate is "photosynthetically active radiation" (PAR).
(3) The PAR system should be based, as was the photometric system, on a single, generalized spectral response curve, which has been shown by experiment to represent the response of an "average plant" with sufficient accuracy for all practical purposes.
(4) All the available data indicate that the photosynthetic response curves of healthy green leaves to equal incident quantum fluxes are quite close to being rectangles bounded by the wavelengths 400 and 700 nm. Therefore, the quantum flux within this waveband should represent PAR, with sufficient accuracy for all practical purposes.
(5) Again by analogy with the history of the photometric system, the next step should be further practical testing of this proposition, using instruments already available, followed by attempts to reach an international consensus, and finally by official adoption by an international agency with power of enforcement.

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I almost hate to say it, but I'm with Corbat on this one. It doesn't bother me that the paper is dated, after all, Newton's Law still applies. But his conclusions state that there is a need for a defined unit to measure the light spectrums utilized by the average plant, and then goes on to define what it should entail. Perhaps we should try to find a specialist in biology.

I don't know how you guys aren't getting this. I give up =/ Good luck guys, I guess it was entertaining..

WAIT WAIT WAIT! I think I found something that may help all three of us. And I think that you will especially like it V.

Photosynthetically Active Radiation (PAR) Units

EDIT: I didn't read it all the way through before posting, because if possible I wanted to prevent any self-destruction of the thread. I like what it says, in fact from what I see, it's what we have been trying to define this whole time. The only problem is that there is no constant for LEDs. Perhaps we can find that elsewhere. But at least it's something.

Wow that's what I've been saying all along! And they quoted McCree too......Are you guys done trying to disprove this guy? He's kind of a legend.....

Well, seeing as I never took any sciences above high school level, and never took physics either, I think I deserve a handicap here. lol But I was not trying to disprove him, I was just being skeptical because it was a proposal, not an explanation of generally accepted 'truth'.

That being said, I see no reason why Corbat shouldn't like it either, it cites the Mol of photons thingy, that he quoted back a few pages.


...Man I could go for a bong with a nice fat bowl packed in it... Stupid bills!