Investing in new lights LED or HID?

[secondtry]

If PPFD is just a lot of words for how much light output in a given area at a given distance within a given EM frequency band, 400-700nm, who cares. A lot of that is wasted energy anyway, green is right in the middle of that, unless the amplitude of the light is equalized to account for that, what are you talking about?

That is a very common misunderstanding of most people, that plants don't use green light. Please see my post above, and the big post on page two. The chlorophyll absorption spectra (peaks in blue and red) are from in vitro spectrophotometer data, not in vivo whole leaf (in the real-life growing situation). The chlorophyll absorption spectra is from an aqueous extract of a leaf, not even a real leaf! That is why we need to use PAS (Photosynthesis Action Spectra) and better yet we could use a curve made from the Quantum Efficiency found in paper above (the green light paper, not the McCree paper).

Adding green light is good, under med-high irradiance from HID green light can/does drive photosynthesis more than red light. That is why I like the Hortlilux Blue 1,000 MH so much: the SPD is great (blue, green peak, red) and it's a 1,000w HID thus PPFD should reach over 1,000 at least (I hope).

If you would have read my post on page two you would have seen all this info already. And you would have seen a good paper funded by the Kennedy Space Center showing if one adds ~25% green light to a LED array there is better plant growth...

Please, read this whole thread, or at least my big post on page two.

HTH

 

[secondtry]

Hahaha, 8"... comparing LEDs and HID at 8" is pretty silly when you can run the LEDs at under 2" from multiple sources.

How many people use LED arrays that close? (answer: very, very few) And considering the wallet I would never do that, talk about a tiny footprint! (how small is your garden? )

rez wrote:

If you don't consider spectrum for considering LED lighting, you obviously missed the whole entire point. To not consider it now is to go ahead and prove the obvious, that they make less absolute power in the visible spectrum. Have you ever seen LED vs HID output plots vs frequency?

Please see my post to you just above this one, you are not correct.

Rez wrote:

Also, if they're not driven insanely and run at high temps, and are from a reputable manufacturers, LEDs will last for years driven 24/7.

I would like to see PPFD and SPD data backing up those claims.

rez wrote:

So even if they do burn-in, it wouldn't matter because they will still have very high output for a very long time.

What you consider "very high output" and what I consider very high output are two different things. To me (and seemingly to cannabis plants) that is 1,500 PPFD.

Just get a bump at the beginning. Also V_f is temperature dependent, so LED power draw is temp dependent, and LED optical output is power and temp dependent, so you better take all this data too when you run your experiments.

What is "V_f"? I plan to hang the LED array at a commonly used distance, ie. as is suggested by LEDGirl , et al. I will test the PPFD from the distance from which they hang their LED arrays, which seems to half a foot at least.

I won't respond to another post of yours if you haven't spent time reading this thread. You have many misconceptions and I tired to provide as much useful and accurate info, yet hard to find in on place as I could.

HTH

 

[renz]

That is a very common misunderstanding most people, that plants don't use green light.

Yeah i know, that's probably why it works for veg and not bloom.

Anyway, check this out, page 8, you electronics dunce, you...

http://ledengin.com/products/5wLZ/LZ1-00CW05.pdf

A white LED is a standard blue LED with phosphor, which produces a very wide area of yellow/green light, with more average power compared to blue, but less peak power. I am supplementing these with 660nm red in a 1:1 emitter combination, soon to be 2:1 in favor of the reds.

Yeah now what, Mr or Ms High-Intensity-White-Light-Is-Better?

LEDs can do high intensity white light too, you know. They can do whatever you need in any recipe you need.

You tell me what a plant wants I'll tell you what LEDs.

 

[renz]

What is "V_f"?

Forward voltage drop of the LED, if you don't know as much or cant do electronic measurements I don't know how people wanting real information are going to quantify you work.

 

[secondtry]

Ignore. If you can't hold an adult conversion than I don't need to see your posts.

Adding white LEDs doesn't equal what the full PAR irradiance (spectral quality) from an HID. Regardless, PPFD is more important than SPD (with caveats I listed above), thus we are back to my main point: I don't think LED arrays can emit enough irradiance (PPFD; in terms of what cannabis likes) at reasonable distances, thus higher PPFD HID is the better choice.

Goodby

 

[mad librettist]

That is not really accurate: science doesn't say bumble bees can't fly, science claims it can't explain why they can fly (yet); I on the other hand can explain the issues of plant-light quantum physics.

bs! Science explains easily why they fly.

 

[renz]

I would like to see PPFD and SPD data backing up those claims.

Asking for SPD data on single frequency LEDs is a little ridiculous isn't it? The colors not going to drift that much if at all over time, so you can just measure its output and check its characteristic frequency and calculate what you need. And LED lifespan is well documented. In fact it is their marketing point so you better believe multi-billion dollar corporations have been researching and documenting this. Why do you think they're converting street lights? Glass tubes are dead in electronics, lighting is just the last straggler.

LED lighting in this case is an uphill battle, but its not over, and while HID efficiency is probably topped out, LEDs will get more efficient for years. You don't seem to know nearly as much about LEDs and probably electronic drive circuitry as you do about plant lighting, so it's understandable you are having trouble seeing the benefits and possibilities. Testing using standard RED/BLUE arrays is probably a waste of time because its been proven they need something else. But LEDs don't just come in red and blue.

 

[secondtry]

bs! Science explains easily why they fly.

'

Whoa...settle down there! haha. It's not like I was saying the sky is falling.

I thought it was that science can not explain why they fly, I thought I watched a MythBusters on that, and I thought I remembered learning it when I was a kid. Maybe since then they discovered it? Hmmm. I am going to check this out. Do you have any link? (not from wikipukeia? )

Thanks

 

[renz]

AND THEN:

If you're measuring power density at fixed distances in a given area, well then it would only be fair if you use higher density LEDs.

Thermal management is an issue, but not too difficult to manage, really.

Something like this emitter perhaps:

http://mouser.com/ProductDetail/LedEngin/LZ4-20R210/?qs=sGAEpiMZZMsgllGlynFdfh5UZljDkryjCtKBjs8cdvk=

4 LEDs in series in a single package under a single lens, and you can space them .75" apart, and purchase optics for them at many angles down to under 3 degrees. And theres no reason you couldn't use a similar setup for plants other than cost.

Hows that for power at a set distance in a set area?

 

[renz]

I don't think LED arrays can emit enough irradiance (PPFD; in terms of what cannabis likes) at reasonable distances, thus higher PPFD HID is the better choice.

Goodby

Yeah you don't think they can but you obviously don't know much about LEDs. =)

 

[secondtry]

RE: Bumblebees:

I just read wayyy to much about this topic. I was wrong on two fronts, I thought the claim was science can't explain it, but the claim is that science says teh bumble bees can't fly (that's kinda silly statement considering they do fly), and I thought science had not yet figured it out:

http://www.theness.com/scientists-report-bumblebees-cant-fly/

Some light has been shed on the origin of the bumblebee myth by author and aerodynamicist J.H. McMasters. (Zetie, ’96) He states that it all started in German technical universities in the 1930’s. Apparently, a famous and unnamed Swiss aerodynamics expert was having dinner with a biologist when the latter asked a question regarding the flying abilities of bees. A preliminary calculation showed that there was insufficient lift to allow bees to fly. Only about one third to one half of the required lift could be generated. The biologist started spreading the word about scientific “proof” that bees can’t fly and somehow the media got hold of the information. Today, decades later it is a ubiquitous myth that is rarely questioned and is often used to disparage science. The implication, of course, is that if “science” (as an abstract entity) claims that bumblebees cannot fly, when they clearly do fly, then “science” is bunk. The findings of science can therefore be comfortably disregarded as esoteric and irrelevant.

 

[secondtry]

@ renz:

I can't see your posts but I do see you are posting a lot. I can only assume what type of posts they are. I want to ask you to stop posting in this thread. It's obvious to me that you are here to pick a fight and won't even be bother to read, nor use accepted science. We all know your stance, LEDs are great and I am a dumb ass. Can you please now go away?

I am sure people would rather have serious discussions than what you offer.

 

[Avenger]

What is the reson you would choose the oceanoptics over the Apogee?

The apogee seems to come with software to calculate the ppfd by considering the RQE relative quantum efficiency, which I think is what you are talking about "QFD is basically PPFD weighted with PAS". Though i know you want to come up with an updated RQE taking into account the shift of efficiency in strong white light opposed to monochromatic light.

Bugbee has done some tests already, maybe we could get his data as a jump start?
http://www.apogee-inst.com/pdf_files/SpectroradiometersEvaluatingLEDlamps.pdf

And i found this and thought I would post it just for fun:
http://www.3reef.com/forums/3reef-f...ed-solaris-lamp-par-comparison-pfo-45882.html

 

[renz]

@ renz:

I can't see your posts but I do see you are posting a lot. I can only assume what type of posts they are. I want to ask you to stop posting in this thread. It's obvious to me that you are here to pick a fight and won't even be bother to read, nor use accepted science. We all know your stance, LEDs are great and I am a dumb ass. Can you please now go away?

I am sure people would rather have serious discussions than what you offer.

You're silly, I already said HID is likely a better choice at this point in time unless you are in it for research/curiosity.

And science says you would test both systems side by side as you would use them in the real world, make observations, make conclusions, have peer review and replication of your studies.

Just taking a light measurement of a random LED panel at a fixed distance doesn't prove or disprove anything about LED tech in general. Not even really much about that particular panel.

Enjoy talking to yourself I guess. =)

 

[renz]

Oh and what I had to offer was a suggestion that people do this themselves because the retail cost is so high, offered help in fabricating the heatsink, because you know, helping people is neat, noted their is available high current LED drivers that are simple to wire up, and that it would prob be greatly appreciated by lots of people if people where to heavily document side by side HID/LED grows that people could base this decision off of.

If these statement insight a fight, well then lets get on with it.

...I just thought this was words on a forum to help a guy decide between LEDs and HID for his future grow.

(Go HID unless you're just into the LED thing for whatever specific reason)

 

[secondtry]

Hey Avenger,

What is the reson you would choose the oceanoptics over the Apogee?

I don't like Apogee much. Their quantum sensors are lower quality than Li-Cor but the main reason I want to use OcaenOptics is (IIRC) Sanjay Joshi suggested them for high quality yet affordable price, and it's the brand but he uses, Sanjay also suggested the quantum sensor from Li-cor vs. Apogee.

OceanOptics come with the "spectrasuite" software to wight PPFD, etc.

Though i know you want to come up with an updated RQE taking into account the shift of efficiency in strong white light opposed to monochromatic light.

Yea. That's great you understand it all, and we are on the same page. I am happy to see you posting, I knew from the single post of yours I read awhile ago you know what is what.

Avenger wrote:

Bugbee has done some tests already, maybe we could get his data as a jump start?
http://www.apogee-inst.com/pdf_files/SpectroradiometersEvaluatingLEDlamps.pdf

Nice graphs! I have read the work of Bugbee, I have his papers somewhere close, I will find them. However, his data is from older lamps, for example, super HPS are not there, etc. IIRC he got some data from a study in the erialy 70's. Hmmm. Let me see what I can find. Although, the spectral efficiency of the lamps (from Bugbee) are probably based upon McCree's original work, where (IIRC) McCree used PPF (umol/m^2) to make QFD (and RQE), not PPFD. We want to use PPFD to make QFD datum and RQE of lamps using the updated PAS. I think Bugbee's work could be very useful, but I think we still need to find our own data considering the use of higher efficiency/power LEDs, HID digital ballasts, etc.

And i found this and thought I would post it just for fun:
http://www.3reef.com/forums/3reef-f...ed-solaris-lamp-par-comparison-pfo-45882.html

That is a neat thread, thanks. I only read page one so far. But a something you may know: what size LED array? I should read the whole thread, maybe later today. One point is PPFD (the author called it PPF, but that's because Apogee wrongly calls it PPF, it's PPFD) would not be representative for how we grow, in that the reflectors used in reefing are to specific size (small) foot prints; this effects PPFD by decreasing footprint. But I am still wanting to read the thread, it looks interesting, thanks.

 

[secondtry]

@ Avenger:

One more thing about that LED thread:

The Apogee has a worse quantum spectral response than the Li-Cor, that is, the weight the li-cor adds to each wavelengths is much more flat than that of the Apogee. This means the Apogee PPFD datum is not as accurate as the Li-cor quantum sensor. And the fact Apogee calls umol/m^2/sec "PPF" is a big warning sign to me, it's PPFD.

The PPFD in that thread is far below what we want, we want ideally 1,300-1,500 PPFD. In that thread he/she found PPFD of 143 at highest (from 1st post), I wonder why the PPFD is so low? And the HID is even lower...hummm, something seems off...I am going to read the whole thread now.

Here are some graphs of the Agogee quantum sensor spectral response (1) and the Li-Cor quantum sensor spectral response (2):

Li-Cor spectral response:

 

[cannaboy]

LED's are the worst thing for marijuana since Arjian.... FACT..

I am Unable to write a plesent comment about crap things.. FACT

by 1 if you want unhealthy plants you can't diagnose the problems of without another light,,, FACT




POINTLESS.......

 

[secondtry]

Choosing a spectroradiometer​

For those who might buy a spectroradiometer here are some tidbits I have collected from good sources who use spectroradiometers all the time (for reefing and herping):

• The unit should be NIST certified to be calibrated.

• Absolute irradiance calibration is needed, ask about it before buying a unit.

Ideal mechanics:

• Optical Resolution: ~< 0.3
• Signal-to-noise ratio: < 300:1
• cosine corrected
• UV corrected spectral response

 

[renz]

LED's are the worst thing for marijuana since Arjian.... FACT..

I am Unable to write a plesent comment about crap things.. FACT

by 1 if you want unhealthy plants you can't diagnose the problems of without another light,,, FACT




POINTLESS.......

If plants use close to all of HID light output, this is probably the case.

But since no one seems to really know, and since there have been successful LED grows, its probably just a matter of tuning the spectrum. And you can do that with LEDs, any recipe you want. Ain't going to happen with HID.

I'm not going to argue that red/blue LED setups are better than HID, but its silly to think LEDs are only capable of red and blue.

If you could find the spectrum that works best, you can copy that with LEDs. With ease. Then you're in a position to do direct comparison studies of LEDs vs HID. At this point, the documentation isn't there for LEDs, and HID is a known working method, so go with that if you need a sure thing.

Also all this talk of measuring LED panels for output, its silly because you can change the focus angle and density of an led array with no drama.

You want to measure vs a typical LED setup, except there is no typical LED setup yet, and setups that mimic HID lighting are probably not ideal.