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Spectrum for red plants

Discussion in 'Lighting Requirements' started by dukydaf, Apr 18, 2015.

  1. dukydaf

    dukydaf New Member

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    I was wondering what light spectrum will enhance red plant growth while maintaining the beautiful colours ? Given the light intensity is high and all required nutrients are in the tank, I have found two options.

    Although I graduated biology, my area of research was not plant science. Maybe there is somebody here who can enlighten me.

    My thinking is this. Red plants will mainly absorb light in the blue spectrum so the peak there is beneficial. However, the red peak will serve to enhance the look of the carotenoids , making them look red not brown. The red peak will also benefit green plants as chlorophyl a and b have their "second" peak absorption in the vicinity. Nevertheless the absorption of red light is higher in water, so maybe option 2 is only useful in shallow tanks. Questions that arise are: Why ADA and other manufacturers promote Option 1 as good for plants ? and Is there a possibility that the red peak prevents plants from turning red (there is useful radiation there afterall) ?

    Option 1 - 7000K - ultra white ( maybe something like this is used by ADA aquasky cannot find a sure graphic of their spectral distribution in english)
    - peak around 425nm
    ultra_white_komplett.jpg

    Option 2 -15000K - blue red white
    -peak at 465nm and 650nm
    ultra_blue_red_white_komplett.jpg

    Thank you for your opinion. Searched the forum and could not find a relevant discussion on this topic.
    PS The Spectral distribution graphs come from this great company called Daytime here in Germany. They have the copyright. I cannot yet post links otherwise I would have included one. If you have any experience if this company please do tell.
     
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  2. Solcielo lawrencia

    Solcielo lawrencia Aspiring Aquascaper

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    In order for plants to appear red, there must be enough red light for the plants to reflect it. No red light = no red-looking plants.

    I use a cool white LED light fixture with a spectral output similar to Option1. The red spectrum is limited and red plants don't look very red. However, when I take a picture using a strobe light, these same plants appear much redder due to the spectral output of the strobe.

    As for what spectrum actually causes the production of anthocyanins, it may be a combination of spectrums, not just blues. I'm guessing that the orange spectrum is what elicits that production, based on using warm white CFLs.
     
  3. Solcielo lawrencia

    Solcielo lawrencia Aspiring Aquascaper

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    UPDATE:
    I switched out 12 cool white LEDs on the fixture with "full spectrum" LEDs (very high in red, almost no green) and red plants turned much redder than ever before. Thus, it appears that it is specifically the red spectrum that induces the production of anthocyanin. Another interesting phenomenon was that internodes became much shorter with the increased red spectrum, helping to create a compact, bushy appearance. So it appears that the red spectrum is very important for the kinds of desirable qualities of coloration and short internodes. So if selecting between various LED fixtures, look for ones with high red output. Single Kelvin LEDs (e.g. 6500K, 10,000K, etc) are very low in red spectrum and thus not suitable for desirable growth. Also note, it is green light that induces long internodes, the tall "leggy" growth of plants.

    This my the current LED selection of the Green Element Quad EVO, 44 - 3w LED, 36" fixture:
    [​IMG]
    27 - 6500K, 12 - "full spectrum", 5 - 475nm blue

    Here is the spectral output of the "full spectrum" LEDs with a 450nm royal blue spike:
    [​IMG]
     
    Last edited: Oct 2, 2015
  4. keithgh

    keithgh Moderator Staff Member

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  5. Williams Favourite

    Williams Favourite Aspiring Aquascaper

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    Very interesting. Thanks for all the useful information.
    Solcielo Lawrecia. Have you made these changes to your led lamp by replacing the leds (DIY) ?
     
  6. keithgh

    keithgh Moderator Staff Member

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    Solcielo lawrencia

    How do you work out what and where to use or is it a trial and error method?

    Keith:):)
     
  7. Solcielo lawrencia

    Solcielo lawrencia Aspiring Aquascaper

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    You're welcome. Yes, I had to remove the old LEDs and solder in new ones I bought from eBay.
     
  8. Solcielo lawrencia

    Solcielo lawrencia Aspiring Aquascaper

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    Selecting the spectrum was simple since light is additive. I knew that the "full spectrum" was exactly like the 6500K LEDs (or any other Kelvin) except with a red phosphor, not a yellow one used in most white LEDs. Thus, the spectral output of the reds VS yellow-greens could be calculated. Since the "full spectrum had similar phosphor content as with a "neutral white" LED, the ratio to provide an even color was about 2 - 6500K : 1 - "full spectrum". I supplemented the fixture with 475nm blue because of the spectral dip in the cyan area. This improved color rendition as well as providing more balance in the blue spectrum.

    As for the placement, the fixture has a low mode where only 12 LEDs are lit. The way I balanced the light was to have half lit with the 6500K and the other half with the "full spectrum", 1:1 ratio. Placing the "full spectrum" on the outer rows was the only way to place the LEDs evenly.
     
  9. keithgh

    keithgh Moderator Staff Member

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    Solcielo lawrencia

    Thank you for all that information, I have never used any lights other than T8 & T5.

    Your information will certainly help others.

    Keith:):)
     
  10. MarcelM

    MarcelM Aspiring Aquascaper

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    I never realy had any real trust in those red and blue full spectrum leds. There yet isn't much real info to find about results other then sales and marketing articles. So i kept it with the white ones in different kinds of K's. I see plants growing under it without much issues. Indeed the typical red plants dont realy get red from the bottom up. So it thought got about the right spectrum but it's just not strong enough to hit the deeper parts.

    But anyway, reading this topic. pulled me over the line.. I ordered me a full spectrum grow light version and give them a try and add them to the current light fixture i'm using. :) Realy curious what results it will have.

    Thanks for sharing your findings.. :)
     
  11. keithgh

    keithgh Moderator Staff Member

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    MarcelM likes this.
  12. Solcielo lawrencia

    Solcielo lawrencia Aspiring Aquascaper

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    Yes, please let us know if there are any changes in growth patterns with the additional red lights. It would be nice to know that the results in my tank are also observed in others. This would provide more evidence that such growth patterns and coloration can be replicated.
     
  13. keithgh

    keithgh Moderator Staff Member

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    Solcielo lawrencia

    I am sure Marcel will document every thing with photos as a back up.

    Keith:):)
     
  14. MarcelM

    MarcelM Aspiring Aquascaper

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    No problemo :) sure ill share my findings. I love experimenting, bought a few before last year (22o volts spotlights) with total 3 red and blue leds p/spot. Only used the for a week, above a small terrescape. But just couldn't believe it would do some and the color they give isn't realy very atractive. So i just stopped using them without giving it much more thought.

    Yesterday i found a collection of gathered articles about led grow lights. One was a short news video from the university of Delft. Where students tried to grow vegtables under red en blue led light only. Farmers where sceptic, but the students pulled it off and grew massive tomatos and cucumbers with it. So the proof is already out there.

    I ordered me a set that fits in the new hanging fixture i builded, not yet installed it :) and see what it will bring.
    36 leds ratio 3:1 - red:610 ~ 720nmnm blue:400 ~ 520nm
    It will be added in the centre with the rest of the white lights, so i hope the red and blue colors are not going to be to dominant in the environment colors. :)
     
  15. keithgh

    keithgh Moderator Staff Member

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    Marcel

    I thought it would be just perfect for you to do.

    When posted it should have a sticky added to it.

    Keith :):)
     
  16. dukydaf

    dukydaf New Member

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    As Solcielo lawrencia himself said, a red light will show more reds in plants. However, if I understood him correctly the red light (used in his Oct. reply) actually increased the amount of red pigments in the plant. Looking at the spectral distribution, there are high peaks in blue and in red. What will happen if the blue light would be even less?



    Now we have 2 different hypotheses:

    1. Red plants become redder because they adapt to convert blue light to usable energy. (Produce red pigments to ‘catch ‘more light)

    2. Red plants become redder because they want to protect themselves from the high levels of red light. (Produce red pigments to protect from light)



    From a biological point of view both are possible, and may happen simultaneously. One can expose plants to high light levels which covers all the spectrum so that the plants go into protection mode. But, here people are mostly interested in using minimal energy to produce red plants. How to best utilize that energy?



    Without a spectrometer, I would suggest to people willing to experiment with red/blue light to use this procedure:

    -before you begin take some of the top leaves from the aquarium

    -photograph them under a control light (a light that will be the same no matter what your tank light)

    - even better calibrate your camera color balance and keep the K the same throughout the experiment, don't alter your photos

    - post photos, and contribute :)

    - repeat the procedure with all your progress



    I will also try to switch blue with red and see what happens (after I re-‘stabilize’ my aquarium).



    * a small mention to my first post. A number of LED types are used in the fixture to create these spectra. Not just one "full´spectrum".

    ** Kelvin is just showing color temperature, it says nothing about photosynthetically usable energy. It gives some hints towards the balance of the spectrum, ie high kelvin suggests high blue proportion. It is useful to describe how we humans perceive light, hot or cool . Using only Kelvin to choose a light to grow red plants is like choosing a racing car only because of its color.



    Feel free to correct and amend
     
  17. keithgh

    keithgh Moderator Staff Member

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    dukydaf
    Red flowering plants usually prefer full sun (this is not always the rule)

    I nature native birds are attracted to red flowers also many new young leaves are red I believe this is to warn of ??? that could eat their leaves.

    In wild fish as they cannot see actual colours only shades of black red is the darkest black.

    A few more thoughts.


    Keith:):)
     
  18. MarcelM

    MarcelM Aspiring Aquascaper

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    Here a rotala in my pond getting day light in colder and less clear water and less ferts, only sun or just filtered sun light on a cloudy day.
    I percieve it as less but it isn't its far more.
    The same rotala in my tank even has other leaf shape, longer and thinner, also thinner stems far less red and more green.
    DSCF4404 (Kopie).JPG

    If you give plants lots of red light the green ones reflect brown adding blue doesn't realy make it more attractive. Green plants need green light to reflect it, if it's not there they wont look green. Even the red plants go more to the brownish side with absence of green. Red / Blue goes purple.. Red / green goes from orange to yellow..

    i have a few plants in my tank with the pottential to go red.. I will see what this full spectrum grow unit will do after a while. That is if its not to dominant over the white lights next to it, if gives the tank and plants in it that odd pale purple color. Then i will not keep using it and settle with only green plants. After all im growing aquarium plants to look at and not cucumbers in there for dinner.. :) It wasn't that expensive so i'll take the risk.. The moment it hangs above my tank and switch it on i'll post a pic.. :) I have no idea what to expect.
     
  19. keithgh

    keithgh Moderator Staff Member

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    Just another thought outdoor plants only does the UV rating have any thing to do with plants.

    Keith:):)
     
  20. MarcelM

    MarcelM Aspiring Aquascaper

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    Did hang the lights today :)
    144 x 65 lummen leds (72 x 10000k, 72 x 8000k) and 36 full spectrum leds 3:1 red/blue ratio.

    It still hangs in make-shift construction, since i do not know what to expect and may change it. Lets test it for a while.. :) And see what the plants do and how they like it. It hangs 1 inch higher than the stand did. So it wont be so much difference i can up de intensity.

    Its more what will the full spectrum addaption do with the (potential red) plants??? We shall see.. Whish me luck.. :D
    The invironmental color is not affected the white lights are stronger and taking over for what i can see.. :)
    DSCF4931 (Kopie).JPG

    DSCF4932 (Kopie).JPG
     
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