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Grow light information Arena here!

beholder
15 years ago

Any of you feel free to place cool information on plant-light physics and artificial-light gardening here. I will post some cool stuff information and discussions I have seen here. I will have to find out how to place photos and here. Unfortunately no PDF's of OCR magazine scan's though. It's exciting! So lets discuss! Later! - Shawn

Comments (73)

  • ralleia
    15 years ago
    last modified: 7 years ago

    shrubs_n_bulbs,

    Thank you for summarizing the NASA report. It helped me to finally understand what the tables and results meant. It would have been nice if they also tested the red wavelength that is commonly available.
    ----------------------------------------------
    I checked out prices on that Roithner Laser site that sells LEDs in a wide range of wavelengths (including 660-700 nm) and have temporarily retreated with my tail between my legs. Ack!

    So instead I sent Philips/Luxeon a pouting email inquiring about future availability of Luxeon emitters with a peak wavelength of ~680 nm. When the giants make it, it will be more affordable. LEDs in the mainstream (human lighting) market is already on the verge of affordibility. They'll get to the plant market sooner or later.

    In the meantime, I hope my 50" luminaires for my 4' CWFs fit nicely in the new 55" wide garden window. Maybe by the time I exhaust my stockpile of fluorescents, LEDs will have made another leap forward. In the meantime, I'll keep reading.

    Neat--Luxeon already replied:

    Good day Mrs. Thompson,

    Thank your for emailing Future Lighting Solutions, your LUXEON® solutions enabler. We are pleased to address your inquiry.

    Thank you for the information regarding plant photosynthesis. Presently our highest transmitted wavelength is 645 nm; as per AB 21. I have also heard that there needs to be a bluish wavelength as well to aid in agricultural growth? If you know this to be a fact, I would like to receive a reply.

    We will be equally pleased to address any future product, power, optical, or thermal inquiries that you might have.

    Regards,

    Paolo Patafie
    Technical Solutions Specialist
    Future Lighting Solutions
    Future Electronics Inc.

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    Okay, here is a little side note on T5 HO tubes, http://www.1stsourcelight.com/downloads/faq-t8t5.pdf. There may be something to ponder here for many. The real issue is getting more light within a greater range of distance. I am hoping to get a nice 8 - T5 unit for the holiday gift extravaganza so I am really getting back into the subject. I am currently using 4 - T8 32W day tubes to grown cuttings.
    Happy growing! - Bhldr

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  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    I am sure that if phosphors "make" the light then LED's will make there stand eventually. Let's hope it is a better world for all of us when the time comes and better plant lighting technology is made readily available. For now I am pretty optimistic about HO T5 technology. There are a lot more choices in customizing the tube fixture with a variety of T5 bulbs. I imagine the Aquarium-Reef community has played the largest role in getting out this technology. After all, much of life did begin in Salt-water. I am glad to see so much positive information getting out to the general public via internet forums such as this. When I was growing ten years ago under lights I could only have imagined this. How far we have come and where we can go! Exciting indeed! Happy growing! Cool forum - http://www.3reef.com/forums/reef-lighting/

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    Text-book Info. on plant physiology explaining in simple terms photosynthesis, spectrum, etc. Can be entertaining too! ;) http://3e.plantphys.net/chapter.php?ch=7

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    A note on Phillips lumiled luxeon site.

  • ralleia
    15 years ago
    last modified: 7 years ago

    I assume that'll be with the program start ballast? How far away from the plants are you trying to get? Even if you managed to get double the lumens there's still that irritating inverse square law of illuminance to deal with. That dratted exponential curve wins every time!

    Other than the raw lumen output (and resulting design flexibility), the issues described in paper regarding T8 ballasts can be remedied by proper selection of a T8 ballast. One can just as easily select an improper T5HO ballast.

    I think you should really try to get the photometric report on whatever ballast/lamp combination you're considering before you buy it. A sample of such data is in the link below. From the right photometric report you can get the data to do a detailed comparative analysis between what you have now and what you're considering purchasing. A new "solution" may not do as much for you as you think.

  • ralleia
    15 years ago
    last modified: 7 years ago

    I forgot to whine about my lighting engineering final scheduled for 12 hours from now. The prof is terrific--so dedicated to helping the students learn, so organized and pragmatic. I wish all my profs had the same characteristics.

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    Colors and Spectral Characteristics of Various Fluorescent Lamps.

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    Broad and General plant grow light overview.

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago
  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago
  • habman
    15 years ago
    last modified: 7 years ago

    Great info beholder.
    nlites site does not appear to be selling these products online.
    Where can I buy these lights?
    The "Bio Tropic 25000K" purple T5 are exactly what I'm looking for.
    I need it !!!!!

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    Yeah, about the "Purple light" post. I am not so sure the nlite is a place where a person would do business. I think they could be pot promoters since I only see the CF 'nurturelight' discussed on "pot" growing sites. I have yet to find any credible company that sells the BioTropic and Nurturelight. It sounds and looks very interesting though doesn't it? That NASA stuff too, hmmm... All interesting stuff but is it in the wrong hands here? I was thinking the "purple" light spectra was similar to what 'ledaero' is experiencing with the red and blue LED's. Interesting...Be safe when you explore!

  • ledaero
    15 years ago
    last modified: 7 years ago

    Thanks for all the information. The purple light seems very interesting, but I also read your posts and I'm now wondering if it's even true. Please let me know what you find out.

    Actually, I'm hoping that there is some evidence it may be true. I have some 405 NM LEDs that purple/blue. I may hook them up and add them to my 470NM Blue and see if it makes a difference. I also see they are claiming increase in the Red and Blue and less green. I'd like to see onre of these purple bulbs.

  • habman
    15 years ago
    last modified: 7 years ago

    Here's a link from a guy who is using the purple CFL.
    Looks like he also has purple tube t12.
    Scroll down to "Step four: Flowering"
    Nurturelite Fluorescent purple 125w

    So yes in europe they do have the purple CFL just not sure about the purple T5.

  • zink
    15 years ago
    last modified: 7 years ago

    It has been a while since I have had time to visit this forum. I have been extremely busy trying to compensate for some of the "downs" in lifes "ups and downs". I have seen this PURple Light site before. It seems a bit purple heavy to me. Score another one for marketing.

    I looked at their page showing the spectrum for the "Bio Tropic 25000K" purple light:
    http://www.nlites.co.uk/images/P1.jpg
    Ignoring a bit of stretching on their graphic, it looks EXACTLY like the spectrum of the Sylvania GRO-LUX Standard lamp, as shown on page 10 of the PDF literature from Sylvania titled "Spectral Power Distributions of SYLVANIA Fluorescent Lamps", or "faq0041-0800.pdf". The link to the PDF had appeared here many times before, but can be seen on:
    http://www.sylvania.com/content/display.scfx?id=003680212
    Or, as a search interestingly showed:
    http://www.nurturelite.com/Spectral_Distrib_Silvania_Fluoro_%20faq0041-0800.pdf
    on the nurturelite site itself.

    The 25000K figure being significantly touted by PURple, really is not useable information, even though it may be a correct number. Everyone should look up a good definition of the word "metamer" to see how Correlated Color Temperature, or "K", can be so nebulous, conferring no real information about the precise wavelength content. I think Sylvania never even bothered to publish any CCT data on their GRO-LUX Standard.

    The phosphors used to create the PURple spectrum are standard, the BLUE phosphor especially. The RED phosphors (actually 2 of them) are rarely used. The one at 626nm (Strontium magnesium phosphate) is often used as the coating on "coated" HID lamps. The taller one at 658nm (Magnesium Fluoro-germanate) seems to be only used on a few lesser-known plant/aquarium lamps.

    I was lucky enough to have Jeff Waymouth, from Sylvania, to look up the design information for the GRO-LUX Standard. That lamp was developed by his father, John Waymouth, and a Greek photobiologist, Christos Mpelkas, many decades ago. If you want to read what he, and other lighting experts said, then go to:
    http://groups.google.com/group/sci.engr.lighting?hl=en
    and enter "zink" in the "Search this group" box. There will be a GRO-LUX discussion somewhere on the list.

    I have found that takes a LOT of time to try and compose a really good and informative dialogue here, if I want to convey technical stuff correctly. I would like to try to return an correct a couple of errors (but not many hah!) that I did make in the past here (particularly a list of wavelengths where I noted UV far into the visible colors I meant to use HG for mercury).

    On a few visits I noticed shrubs_n_bulbs had really been getting into disseminating information at every turn. Good job shrubs! It takes a lot of composing time to get your info right, which I havent had time for lately.

    Zink

  • ralleia
    15 years ago
    last modified: 7 years ago

    The following is a portion of the text from an interesting patent (US #6921182) on LEDs for plant growth. I don't know if they're right or wrong, but it's food for though in trying to find home in on an effective wavelength for plant growth at an affordable cost:
    -----------------------------------------------
    660 nanometers (nm) is the wavelength that drives the engine of the photosynthetic process. The 680 nm wavelength is perhaps closer to the peak absorption wavelength of one of the two chlorophylls found in higher plants. However, at 680 nm you miss completely the absorption curve of the second chlorophyll, and furthermore the output curve of a 680 nm LED has a fair amount of light output above 700 nm, which is known to cause unwanted morphological changes to plants. LEDs of 680 nm output are also rare in the marketplace, making them relatively expensive. Our choice of a 660 nm first wavelength component is a compromise wavelength commonly used in plant growing research, which supplies energy to both types of chlorophyll without emitting enough light above 700 nm to adversely affect plant growth.

    The 620 nm LEDs used in the aforesaid Ignatius et al. patents, are meant to provide the light energy for photosynthesis, but a look at the absorption spectrum for the two chlorophylls shows that this wavelength falls almost entirely outside the absorption curve for chlorophyll.

    Our research showed better results using LEDs of 660 nm and 612 nm rather than the wavelengths of 620 nm and 680 nm. Beneficially, LEDs of 660 nm are also readily available in the market, and are very inexpensive.
    ---------------------------------------------------------

  • ralleia
    15 years ago
    last modified: 7 years ago

    A very interesting article on pepper physiology as a result of growth under different spectrums of light: Metal Halide, and three different LED mixes. I'm afraid I don't understand the botanical science well enough to really understand.
    --------------------------------------------------------
    Abstract:

    Pepper plants (Capsicum annuum L. cv., Hungarian Wax) were grown under metal halide (MH) lamps or lightemitting
    diode (LED) arrays with different spectra to determine the effects of light quality on plant anatomy of leaves
    and stems. One LED (660) array supplied 99% red light at 660 nm (25 nm band-width at half-peak height) and 1%
    far-red light between 700±800 nm. A second LED (660)735) array supplied 83% red light at 660 nm and 17% farred
    light at 735 nm (25 nm band-width at half-peak height). A third LED (660)blue) array supplied 98% red light
    at 660 nm, 1%blue light between 350±550 nm, and 1%far-red light between 700±800 nm. Control plants were grown
    under broad-spectrum metal halide lamps. Plants were grown at a mean photon ¯ux (300±800 nm) of 330 lmol m−# s−"
    under a 12 h day-night photoperiod. Signi®cant anatomical changes in stem and leaf morphologies were observed in
    plants grown under the LED arrays compared to plants grown under the broad-spectrum MH lamp. Cross-sectional
    areas of pepper stems, thickness of secondary xylem, numbers of intraxylary phloem bundles in the periphery of stem pith tissues, leaf thickness, numbers of chloroplasts per palisade mesophyll cell, and thickness of palisade and spongy mesophyll tissues were greatest in peppers grown under MH lamps, intermediate in plants grown under the 660)blue LED array, and lowest in peppers grown under the 660 or 660)735 LED arrays. Most anatomical features of pepper
    stems and leaves were similar among plants grown under 660 or 660)735 LED arrays. The effects of spectral quality
    on anatomical changes in stem and leaf tissues of peppers generally were correlated to the amount of blue light present in the primary light source.

  • ralleia
    15 years ago
    last modified: 7 years ago

    Sounds rather hokey, but if there's any truth to it, the "synergy" might help drive down the price.

    Two sources--I haven't obtained technical specs from either yet:

    https://plus37.safe-order.net/heelspurs/a/led/led_research.html#630

    http://photoman.bizland.com/660array.htm

  • ralleia
    15 years ago
    last modified: 7 years ago

    It looks like the latter source is based on the SunLED XLZR12WF (http://www.us.sunled.com/products/spec/XLZR12WF.pdf) with an output of 4000 mcd and a 20 degree beam angle. Put 672 of these together and you get a whopping 257 lumens according to my calc's. UGH.

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    Nice article on the Peppers! Good find on the website too! I did post an outside note on the purple light in the general light forum, you can see if there is any other info. there. I did get some emails back from a few person's who offered to sell me some "Purple" lights and one also named a manufacture. It still seems that quality control is lacking though. I really don't want to buy from a source that has not been around or can be vouched for. I really prefer to buy from the larger manufacturer's as they seem to have the best quality of light bulbs. So, even if the Purple lights are there I would prob. still buy the standard high quality bulbs.

  • beholder
    Original Author
    15 years ago
    last modified: 7 years ago

    I really wonder about my post here. I cannot say I made it with a clear conscience.
    Here is the story behind this post. I had just had an exciting day visiting a previously unknown Hydro Supply store locally. The owner gave me 14 Hydroponic supply magazines and catalog's and I was elated to know the world again.
    Sadly I did not know it was all childish hubor (once again :() and what information the magazines had was a mix mash of adverts and slanted reviews.
    I really knew nothing whatsoever to do with the specifics of lighting! In fact I was rather clueless. How absurd you might say, you would be correct.
    So, I hope some confusion can be cleared and we can get on with our lives!
    I really wish they would put a after post edit capability on this forum! I would have corrected the error's of my naive hubor long ago! ;)
    - I am only too human in an inhumain world. But that is no one's/things fault "per say". ;) Feel free to Laugh, cry, or vomit...

  • ledaero
    15 years ago
    last modified: 7 years ago

    I seem to be getting good vegetative growth using the 630 NM Red and 470 NM blue. The more blue I give it the better for foliage it seems. I did an experiment on my peppers. I had them just under the red for a couple weeks and they were surviving, but not much action. Once I turned the Blue on directly, they took off on another veg spurt and got real bushy and started blossoming again. I have some young cucumbers doing pretty well also in the early stages.

    Although 660NM seems it might be the best from the research articles, they are available, but not that cheap and not that powerful (at least what i can find). The best price I found was $35 for hundred at 2500MCD, 20 degree viewing angle.

    The real challenge I feel right now with the LEDs is the blossom/fruit set stage. I was able to get a couple dozen Tiny Tim tomatoes to set, but that's not very many for one plant. I cannot get a pepper blossom to set yet. The peppers I am trying are miniature chocolate bells.

    Another problem I have is I'm a rookie on Hydroponics and Aeroponics anyway. So, basically I can't be guaranteed that I'm doing everything else right yet! It's very likely that I could have problems even under the real SUN!!!

  • shrubs_n_bulbs
    15 years ago
    last modified: 7 years ago

    Although 660NM seems it might be the best from the research articles, they are available, but not that cheap and not that powerful (at least what i can find). The best price I found was $35 for hundred at 2500MCD, 20 degree viewing angle.

    You can't easily compare LEDs at far red wavelengths using MCD. 2500MCD at 660nm is equivalent to over 10,000MCD at 630nm. Those LEDs are probably better than you think! At 670nm, you have to double the MCDs again, and again at 680nm and again at 690nm (very roughly) to compare in terms of photon fluxes. Actually I'd be surprised if you find a 690nm LED which will show you MCD output becdause it is so meaningless, probably they'll just quote a radiant output in mW. You also have to check the viewing angle, half the angle means a quarter of the light. I've seen 625nm LEDs at 30,000MCD (2.2V/50mA) but only an 8 degree viewing angle, probably giving less total light than your 10,000MCD version.

  • ralleia
    15 years ago
    last modified: 7 years ago

    Hey ledaero,

    Part of your issue with the peppers might be that they're bells. Somewhere on one of these forums I read that they're more difficult to get to set fruit indoors. You might try a non-bell variety, like a Cubanelle. If you send me an email with your address I'll mail you some seeds of cubanelle to try, along with whatever other non-bells are in my freezer downstairs. I think those thin chili pepper types would be even better, but I have no seeds of those types because they're too hot for me.

  • ralleia
    15 years ago
    last modified: 7 years ago

    SunLED has 660 nm LEDs that according to one of the sellers of assembled arrays has very reasonable prices. It's a ~4000 mcd LED with 20 degree beam angle with 20mA.

    The seller stated that it has independently tested at the following optical outputs:

    20mA = 5.2 mW
    25mA = 6.4 mW
    30mA = 7.8 mW

    I signed up for SunLEDs catalog for some educational reading, but haven't received a reply yet. The link is available below. Perhaps they may have other further red LEDs as well, which shrubs_n_bulbs says will be more effective for plants. (up to the cutoff somewhere around 700nm).

    BTW Shrubs_n_bulbs, I just wanted to thank you for all the insightful input that you provide this forum. Your posts are always valuable reading and show your experience and knowledge in plant growth lighting. Don't ever go away!

  • ledaero
    15 years ago
    last modified: 7 years ago

    Thanks all for the helpful information.

    Shrubs_n_bulbs - do you have some links on some details of calculating the photon flux or is there a formula to get photon flux using wavelength, viewing angle and MCD or how can I do it best?

    Ralleia - thanks for the pepper tip and the SunLed link. Maybe I picked too hard of a challenge for my lack of experience...I'll email you thanks!

  • shrubs_n_bulbs
    15 years ago
    last modified: 7 years ago

    This table gives the relation between radiant power and lumens at different wavelengths. Note that lighting lumens are photopic, although you will occasionally see comparisons made using scotopic lumens. You will see the value of 683 lumens/W at the wavelength of 555nm, this is the definition of a lumen and also the theoretical maximum efficiency of a light source at that wavelength. White light must include a spread of wavelengths (or at least three wavelengths such as RGB) which the eye doesn't perceive as well, so the maxiumum theoretical efficiency of a white light source is less than 400 lumens/W.

    The conversion to photon fluxes is simply to multiply by the wavelength, longer wavelength means more photons per watt of radiant power. If you want an actual number of photons then you have to multiply the power in watts by the wavelength in metres (nm / 10^9), then divide by 6.626 x 10^-34 (planck constant), divide by 3 x 10^8 (speed of light). You'll get an absolutely huge number of photons/sec, divide by 6 x 10^17 to get micromoles/s. Cutting out the middleman, radiant power in W, times wavelength in nm, times 4, gives micromoles/s.

    Converting candela (or milli-candela) to lumens exactly for a directional light source such as an LED is almost impossible. The mcd value is a peak value at the centre of the beam and you can only make a very rough estimate of the brightness over the whole viewing angle. Similarly, comparisons between the total light output of LEDs with different viewing angles is very approximate. The solid angle calculations are a bit of a pain, but this calculator will give you some reasonable numbers.

  • ledaero
    15 years ago
    last modified: 7 years ago

    Shrubs_n_bulbs,

    Thanks much for the info and links!

  • yourgrowbro
    15 years ago
    last modified: 7 years ago

    I fould that the best way to find out information about led grow lights is from the companies that commercially produce they. of course as many of you have found out they don't exactly give out their trade secrets to just anyone but there is one place where any smart company must will tell every detail of their product to and that is the united states patent office. if you try to search for "led grow lights" at the patent search web site you will come up empty handed. so if you want the really good stuff you have to find a product that someone alrady has a patent for. I accomplished this through putting the products name and "patent number" in as a search query and would you know it there it was, so then all you need to do is go back to the patent search page put in that number and your good to go. the best thing about Patents is that inorder to be granted one you must give grave detailed descriptions and grahics as to why and how the company changed there product design so that most likely it worked better the another one. give it a try you'll be amazed. Peace....love....Happiness

  • tybeho
    15 years ago
    last modified: 7 years ago

    Is it safe to use metal hallide bulbs without a lens? If not, is the danger from fire or mercury? Thanks

  • watergal
    15 years ago
    last modified: 7 years ago

    It is safer to use a lens. This protects the bulb from bumps or stray water droplets that could cause it to explode. If the bulb cracks, it puts out UV radiation that is very bad for your eyes; if the bulb breaks, you get hot flying glass shards, which is just plain bad all around! A lens helps protect you from both. I would not run mine without a lens - in fact, I paid more for a fixture that could use a glass shield; many of the cheaper ones can't.

  • shrubs_n_bulbs
    15 years ago
    last modified: 7 years ago

    The "lens" is for protection from intense UV, semi-molten bits of flying glass, and I suppose mercury vapour, not to mention several hundred watts of exposed electrical arc. It should be considered essential for metal halide bulbs unless they are "O" (for open) rated, since metal halide bulbs frequently fail explosively. O-rated bulbs are becoming more common and have a built-in envelope that keeps the UV, hot glass, and mercury contained if the inner bulb fails, also circuitry to shut down the arc quickly in the event of failure.

    Bulbs that require a separate glass shield are marked as "E" or "S". The bulb sockets are subtly different with the intention that bulbs are not used in a socket where they wouldn't be safe, but it is often possible to remove the shield from protected lamps if you have a death wish.

  • tybeho
    15 years ago
    last modified: 7 years ago

    Thank you both very much, especially shrubs n bulbs for the tip about O-rated bulbs.

  • ralleia
    15 years ago
    last modified: 7 years ago

    Hey ledaero,

    Just wanted to let you know (for the purposes of your pepper experiment) that 2/2 (two out of two) North Star and 1/2 Cubanelles pepper plants have set fruit. They're all grown under close fluorescent light, mostly bright whites. The plants seem somewhat dwarfed under the conditions--they only got about 1 foot tall and started popping out flowers. I thought that my outdoor plants got a bit taller last year before flowering, but I could be wrong.

    The fruits might be similarly small, but they're still growing.

    I have yet to get a single ripe tomato off all the indoor tomato plants. I have a couple dozen growing green fruits, but none have started to change color.

    All the plants were started approximately 1 November.

  • ledaero
    15 years ago
    last modified: 7 years ago

    I've been heads down working on my LED lights and have got great results! I built a really powerful RED LED light at 630NM and have the bell peppers blossoming like popcorn and at least 3-4 dozen small pepper fruits have set on the two plants. A couple of the chocolate bells have gone green to brown and soon will be Red and ripe. I now have excellent veg/grow blue lights figured out and now I think the blooming is there too. If you want to check out these results see HTTP://www.greenpinelane.com where I have photos of all the above. It's been a long haul, but things are really looking up on the LED side. What are most promising as far as growth rate are the 3 watt High power LEDS in a collimator and lens that really put out the FC. They cost a whopping $15 dollars each and look like they are providing enough light for one plant (cucumber right now). Thanks everyone for the info provided on this forum, it really helped a lot.

  • shrubs_n_bulbs
    15 years ago
    last modified: 7 years ago

    Wow, you've gone at this big time!

    You really need to convert those lux readings to photon fluxes. Do the blues look brighter to the naked eye? Hard to compare I know, but that's what the lux readings say. Lux (=foot-candles x 10) can be pretty misleading for monochromatic light in the blue and red ranges. Conversion rate (no units, just relative levels for comparison) at 470nm is 1/62 and at 630nm is 1/180, which suggests the blue LEDs are putting out a LOT more photons than the reds. But even slight variations in the wavelength can make a big difference. For 460nm the factor is 1/95 and at 640nm it is 1/120. Those PlasmaLEDs look to be way more efficient than the GroovyGrows.

    Your burnout was almost certainly due to heatsinking problems. Might be inherent in the bulb, might be that it needs mounting a certain way.

  • dcarch7 d c f l a s h 7 @ y a h o o . c o m
    15 years ago
    last modified: 7 years ago

    Many reasons why LEDs burn, insufficeint heat sink is one. The others:

    1. Manufacturer intentionally overdriving the LEDs.
    2. The design does not have a good electronic driver circuit to limit current and voltage.
    3. the LEDs are plug into the same outlet circuit with other heavy inductive load appliances such as refrigerator, air conditioners.
    4. Thunder storm inducted surge in you household electric system.

    dcarch

  • ledaero
    15 years ago
    last modified: 7 years ago

    Thanks Shrubs and bulbs -

    I'm only using the meter to compare 'like' bulbs right now. For example, I'm not comparing a 470 to a 630, just comparing all 470s against each other. The 3 watt plasmaLEDS are pretty cool, great quality, and they work darn good.

    The ones that burnt out were from BESTHONGKONG - real crap is waht they sell and #2 reason from Darch is their problem

    I have not had a PLASMALED, Groovygrow or traffic light ever burn out or fail in any way yet.

  • ralleia
    15 years ago
    last modified: 7 years ago

    ledaero,

    Thanks for the synopsis on besthongkong. I looked into their stuff following a lead from an LED enthusiast but stopped researching them after finding some gross incongruencies in their advertised numbers. Happy to know that the source can be ruled out for future research...

    Hey, I've been getting lots of little red 'maters for the past couple weeks with excellent flavor off the Red Robins! They're not as quite as good as my summer Black from Tula 'maters, but they're packed with flavor when compared to the supermarket tomaoes this time of year. The biggest trick is resisting the urge to pick them underripe--the full flavor develops when they're truly red. I'm pleased to find that they *DO* still develop that flavor when grown indoors.

    The biggest North Star pepper fruit is now over 2" long. I don't plan on harvesting any of them until I see a hint of color change so I know that they've achieved full size.

    I'll try to post some photos today...

  • ledaero
    15 years ago
    last modified: 7 years ago

    ralleia,

    I'm happy you did not buy any besthongkong. The few I bought all burnt out. Worse yet, they don't even have the decency to answer my emails to their support.

    The prices are coming down on the Luxeon stars to about 3.00 apiece for the 3 watters. Then optic lenses are only a couple of bucks. So, I'm thinking of putting some of those together for some blue lights. The High power Reds at 625 NM seem too low range though. I seeem to have luck at 630NM. I know it's close, but 625 NM seems to do nothing.

    Congrats on the tomatoes. Isn't it nice to have a vine ripened tomato in the winter!

    I know what you mean about the temptation to pick too soon. My mini chocolate bells get green, then brown, then red-brown. They are good eating at all colors, but they are really the best at the red-brown stage, but waiting is hard! They continue to blossom and set still, so I'm finding I have quite a continual supply of them coming out for quite a while now.

    My tomatoes are doing okay and are about 7-8 inches high now. Two are Red Grapes which seem to be growing really well and one is Tiny Tim that seems a little stunted. I am trying a new machine, new nutrients, and new lights on them so I have so many factors to figure out to get right.

  • deweymn
    15 years ago
    last modified: 7 years ago

    Wow! Too much info here. My head is about to explode.

    Any of you debaters want to summarize what was discussed?

    A graph? KISS

  • ralleia
    15 years ago
    last modified: 7 years ago

    ladaero,

    Since "Tiny Tim" is a dwarf variety, the "stunted" appearance that you're describing may be just normal for the variety. All my Red Robins (another dwarf variety) were stouter with smaller leaves than the standard tomato varieties.

    I've harvested a couple of the peppers off the Cubanelles and the north stars. They're incredibly crisp and a bit more pungent than I would expect for sweet peppers, but oh, so fresh!

    Last week my new 6' wide garden window was installed, so I'm temporarily running without any supplemental light. In the fall I'll once again have to revisit the LED v. fluorescent v. HID supplemental light choice. By that time we may have new selections.

    For eating, I found "Tiny Tim" to be worse than flavorless. Red Robin is ok, but lately I've found the tomatoes I've picked off my indoor plants to be watery and weak-flavored. My toddler has started rejecting them, so the plants are soon bound for the compost. The "Gardener's Delight" indeterminates have started producing just a few small but delectably-flavored fruits. The "Orange Pixie" plants, though they produced well outdoor, were a big disappointment for indoor winter growing.

    Next winter I plan to grow strictly indeterminates on sturdy indoor trellises, along with a few pepper plants for fresh eating. I'll try Gardener's Delight, Pink Pink Pong, Yellow Pear, and Tommy Toe. I've now got over 12' of south-facing windows and will set up supplemental light again.

  • bigal_grow
    14 years ago
    last modified: 7 years ago

    Anyone had any experience with these lamps?
    E27-1W7-RB
    http://www.quasarled.com/led-grow-light.htm

    I think they may also be the same as these:
    http://stores.ebay.com/New-Leaf-LED-Li-Leger-Inc
    NEW LEAF VII
    If the link is broken you can find it by doing a Google search for "new leaf 7 Watt High Power LED Grow Light"

    They claim to have six 660nm (red) LEDs and one 455nm (blue) LED. Each 1 Watt LEDs.
    I ordered some from Quasar and opened one unit up. All the LEDs are in series and the total current is just above 300mA.
    BTW the quality and consistency of manufacturing is what you'd expect from mainland China:
    1. The cast aluminum body has thin sections where the casting is not great and light shines right thought the back of the lamp in a couple of places.
    2. During assembly someone used inconsistant length screws holding the lamp together.
    3. The packaging is so bad that some of the lamps I received could not be screwed into a lamp socket as the screw thread was crushed.
    4. One of the lamps had a faulty inverter which was overdriving the LEDs (680mA instead of 300ma for the others)
    5. The LED lenses are not glass, just plastic and are claimed to have a 30 degree pattern, which is a little too tight, looks like they'd be best to go for 40-60 degree lenses for illuminating a reasonable sized plant.
    6. The LEDs are soldered to a printed circuit board and white thermal compound has been put under the LEDs to help with the thermal transfer. However I cannot be sure that the printed circuit board is thermally conductive, it might be, as it is a funny black color, perhaps not regular fiberglass... or maybe just a dark solder mask to throw me off the trail... But in any case application of the thermal compound is inconsistant - some of the lamps had little or no thermal compound under the LEDs, so no doubt those ones will run hotter and have substantially reduced life. The printed circuit board is held in place against the cast aluminum by the force of the lenses pressing down on the LEDs when the cover is screwed in place. The underside of the printed circuit board is generously smeared with thermal compound.

    The red light is very bright, and seems too bright for 660nm light, I suspect these are not actually 660nm LEDs but perhaps regular ~624nm ones. What I read on Internet was that because 660nm is getting close to the edge of human color perception, an equivalent light intensity to regular red (624nm) will seem a lot dimmer.

    Apart from roithner-laser's C11A1-660-30 (no doubt very expensive) I am unable to find any manufacturer anywhere claiming to have 1W 660nm LEDs which look remotely similar, which also makes me suspicious.
    Opening the grow lamps up, I closely inspected the LEDs and found they are a white body LED, flat on the bottom, with flat gold connections emerging from each end. They have a small rectangular pressing in one of the leads to recognize the positive side. They look pretty similar to these ones:
    http://www.hebeiltd.com.cn/led.datasheet/E12GR2C.pdf
    I contacted Hebei (the Chinese manufacturer) and they told me they do not have a 1W 660nm LED, only 624nm, and they said they know of no other manufacturer that does have them.
    Also the blue lamps listed on Hebei's web site are described as Royal Blue 460nm (not 455nm) so if the manufacturer of these grow lamps is using Hebei LEDs then I am dubious about their claim of the light wavelengths.

    I am tempted to have the wavelength of the light tested to confirm the manufacturer's claim.

    Has anyone seen these lamps?

  • object16
    14 years ago
    last modified: 7 years ago

    You guys are getting too carried away with wavelengths - now repeat after me: there is no magic optimum wavelength for photosynthesis. Because of billions of years of evolution, plants have adapted themselves to use (now pay attention here): all wavelengths just about equally well. The only additional use that LED's have is in (pay attention again) - photomorphogenesis. Google is your friend here, look this up and all will be confirmed on the internets. If you wish to manipulate the phytochrome red pigment between Ph fr and Ph r, then go buy yourself some 730 nm leds, these are useful in industrial growing of cannabis, and no, I am not high on pot, I have not been high for over 2 years since LEO shut me down, but I still know a lot about growing. Blue light is useful ONLY because it is required to synthesize chlorophyll, but you don't really need very much. Now click on the link and observe the glory of 5 billion years of evolution, all in one nice graph. Now just find out how to optimize the greatest number of photons per watt, and you will be in business!!!

  • lermer
    14 years ago
    last modified: 7 years ago

    (Shrubs) "You need to go and read some more about
    photosynthesis. One blue photon produces the same chemical
    end result as one red photon."

    (Lermer) I hate to interrupt Shrubs' heroic refutation of
    LED claims (shockingly I find myself generally agreeing
    with him on this), but each photon carries an energy that
    is described by Planck's equation:

    Q = hc/wavelength in meters
    where Q is the photon energy (joules), h is Planck's
    constant (6.623 x 10 to the minus 35 J s), c is the speed
    of light, over wavelength in meters. Figure 2.1, chapter 2
    of Light Measurement Handbook (1998), shows a direct
    linear relationship between wavelength in meters
    (spectrum) and photonic energy. The more toward UV, the
    more energy; the more toward infra-red, the less energy
    per photon.

    From "Photosynthesis" (1987), fourth edition, by D.O. Hall
    and K. K. Rao, chapter one, page 6:

    "The energy of a single quantum of light or photon is the
    product of the frequency of light and Planck's constant,
    i.e., E = hv. Since frequency is inversely related to
    wavelength, it follows that photons of short wave length
    are more energetic than photons of longer wavelength, ie,
    at one end of the spectrum photons of blue light are more
    energetic than those of red light at the other end."

    (Lermer) For any given pulse of light, the blue light is
    slightly ahead of the red light. So, the blue acts like a
    spearhead, penetrating the leaf and carrying the rest of
    the spectrum with it. That does not mean, blue light by
    itself is more efficient for plant growth; but it has
    specialized functions.

  • lermer
    14 years ago
    last modified: 7 years ago

    This is the context of the exchange between "Shrubs" and
    another poster:

    "Red photons have less energy than Blue. This is why lots
    of red and a few blue are needed as blue contains more
    energy for the plant to use. The plant has to collect more
    low energy Red for the light needed for further chemical
    reaction."

    (Shrubs) Sorry, but this is garbage. You need to go and
    read some more about photosynthesis. One blue photon
    produces the same chemical end result as one red photon.
    The excess energy is lost as heat while being transferred
    to the ultimate photosynthetic receptors.

    (Lermer) I also disagree with the top post, but Shrubs'
    refutation is misleading. Blue spectrum does have more
    energy than red spectrum. But the reason plants need red
    more than blue, is that they have evolved under a forest
    canopy and red penetrates the canopy better than blue.
    Because red bends better. So it is the most efficient
    single spectrum. Blue is the most important single
    spectrum, due to it's specialized functions.

    One blue photon does not result in the same chemical
    reaction as one red photon. Each portion of the spectrum
    results in a different chemical reaction. Lack of a
    specific spectrum is compensated for by chemical processes
    (at a loss to efficiency).

  • jkirk3279
    14 years ago
    last modified: 7 years ago

    "Because of billions of years of evolution, plants have adapted themselves to use (now pay attention here): all wavelengths just about equally well."

    That's completely wrong, of course.

    Let's try a thought experiment:

    Suppose chlorophyl was 'magic' and could in fact absorb all wavelengths of light perfectly.

    Then foliage would be black in sunlight, wouldn't it? No light would bounce off, so no reflected light would reach your retina and you'd experience the color of the leaves as "black".

    But in normal sunlight, foliage appears GREEN.


    Now, as it happens the foliage under my LED Red/Blue arrays DOES show up as a very dark greenish black -- the effect is to make the leaves look like they're made of very hairy black leather.

    Which suggests to ME, that the chlorophyl in the leaves is in fact absorbing the LED light pretty well. Only a fraction of the light is reflected.

    (Place a white index card next to the leaves, and it reflects purple light back at you. The light reflects off the paper, but not off the leaves. So it's being absorbed.)


    But turn on the fluorescents, and suddenly the plants are bright green and healthy looking.

    Now, with these results, we should ask ourselves WHY the blue and the red LED light is absorbed better than, say, green and yellow light.

    Well, imagine this: light absorption is an electro-mechanical process. Light shines on chlorophyl and the molecule is excited.

    The energy thus captured is used to drive chemical reactions.

    To perfectly absorb sunlight, you'd need a molecule specifically tailored to each frequency of sunlight, and of course that's not the case.

    Instead there are a few variants of the chlorophyl molecule, a, b, c1, c2, and d.

    Between them they manage to capture some frequencies of blue and red light pretty well.

    There are some alternate dye molecules that can store excess energy for very brief periods, in other frequencies. You see those dye colors in the Fall when the leaves change colors.

    But still, there's a wide frequency range that chlorophyl can't capture, and since that range is centered on the color green, that's why foliage looks green.

    Suddenly, I wonder if someday a bright chemist could synthesize a brand new form of chlorophyl that improves light capture efficiency in the green frequency band.

    Add that new molecule to a plant's genome and maybe you could achieve food plants that could survive in shade or during shorter growing seasons.

    It's an interesting idea, but of course plants can't deal with bright sunlight as it is. They have mechanisms to deflect bright sunlight and discharge excess energy before the excess causes the cellular mechanisms to oxidize to death.

  • tflinton
    14 years ago
    last modified: 7 years ago

    Ultimately I think led's can grow a plant, but I think a full spectrum is probably best. Go with a hortilux HPS blue or Ceramic Metal Halide HPS retro.

  • snowdruid
    13 years ago
    last modified: 7 years ago

    @jkirk3279
    you are wrong as well: light is a biochemical process its a (photochemical process to be exact)and under no circumstances a electro-mechanical.in fact there is nothing either electric or mechanic about photosynthesis (REDOX yes but not electric). furthermore the colorful "dyes" as you call them are called pigments and they come in all sorts of colors (absorbing in different NM ranges from chlorophyll). pigments are NOT monochromatic they absorb a short range of wavelengths so you would not need one for each wavelength.
    In fall the green chlorophyll pigments are broken down, the green color vanishes, which makes the secondary pigment (red-yellow) visible.
    as far as i know geneticists (not chemists) are working on a) optimizing chlorophyll absorption and b)adding secondary pigments to plants for hi-yield biomass production.
    im currently working on an algae project and this forum was very helpful. however i wonder what led efficiencies are right now compared with when this tread started.
    im not very good with numbers so a "quick and dirty" formula for converting mcd and opening angle to photonic flux ( mumol photons/(m2-s) would be greatly apppreciated.

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