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Thread: Lights again

  1. #1
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    Lights again

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    Topic on what is the suitable light have been discussed before here.

    http://www.aquaticquotient.com/forum...spectrum+light

    I tried following the thread as closely as I could. What I gathered is, we need lights between 6500 to 10,000 k for growing plants. And most recommend a daylight tube (white) as the best choice so that the full spectrum of the light can be provided to the plants.

    Then I read this on a horticulture website:

    Plants appear green because they reflect green light, while absorbing the other colors of the spectrum. The green pigment in plants is chlorophyll, essential for photosynthesis. The green portion of the light spectrum is relatively unimportant to photosynthesis, since it is mostly reflected by the plant. Chlorophyll absorbs light energy from the blue and red portions of the spectrum to convert carbon dioxide and water into sugars to be used by the plant. Without red and blue light rays, the plant will weaken or die prematurely.

    The orange-red portion of the light spectrum is very important to plant reproduction. Pigments called "photochromes" absorb the red and far red portions of the light spectrum. Photochromes regulate seed germination, root development, tuber and bulb formation, dormancy, flowering and fruit production. Therefore, the red portion of the light spectrum is essential to plant growth, particularly during the flowering, fruiting and reproductive stage.

    Plants need light from the blue end of the spectrum as well. Blue light stimulates chlorophyll production more than any other color, promoting thick leaves, stocky stems and strong vegetative growth. Carotenoids, the yellow-orange pigment in plants, absorb blue light and control leaf fall and fruit ripening. Riboflavin, containing another pigment, absorbs violet light and influences "phototropism", the movement of plant foliage in response to a light source.
    Now, if you can only choose to have 1 tube, then it makes sense to select a white color tube so that you can provide both the orange/yellow and the blue end of the spectrum to the plants.

    However, what if you can have several smaller tubes of lights? Would it be better then, to have a mixture of warm white (more yellowish) and cool daylight tubes (more blueish) tubes than to have all daylight (white) tubes then? Has anyone experimented with this? Would like to hear from you.

    cheers

  2. #2
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    IMO,

    If you mix different kelvin tubes, its more for the aesethetic reason. If all the tubes that you are going to use does have the yellow/red & blue spectrum, I do not see why its not possible. Since photosynthesis occuurred at wavelengths from 400-700 nm. Unless, you are using a Marine Actinic tube, which typically only have wavelengths 400 - 480nm. Under such lightings Photosynthesis maybe crippled. Thus if you replace one of ur tube with actinic, the overall PAR will also be reduced.

    Below are some chart I extract from Arcadia webbie.

    Plant Pro (~6500K)


    White (~10 000K)


    Actinic (~20 000K)


    Do note that these are T5 bulbs and different makers typically have some variations.

    Cheers
    JC

  3. #3
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    These are from ATI.

    Sun Pro (~6500K)


    Aquablue Special a.k.a white (~11 000K)


    Actinic Blue (~20 000K)


    Cheers
    JC

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