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Importance of k values in lighting.

Discussion in 'General Plant Topics' started by Afroturf, May 5, 2007.

  1. Afroturf

    Afroturf Junior Poster

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    I am planning a 200l tank and will be going for a jungly style and will be using all low light plants, lots of moss 5-7 crypt speciels and a couple of large Echinodorus plants.

    I want the tank to look quite subdued in terms of lighting I know that many believe that bulbs with a K value around 6500k are best for plants but i know that this will not give the type of light I disire. How ever I believe that a 4000k cool white light would. But would this be of a detrimental effect on the growth of my proposed plants?

    I have 1 x T8 30w unit and 1 x twin 36w compact T5 unit.

    I currently have a Aqua glo tube for the T8 which i think gives off the perfect brightness of light but it is a bit pink.

    These are the tubes that i am considering for the compact t5 unit -

    ASL plant light, K8000 and K12000
    Philips or Sylvania, 4000k cool white light
    Philips or Sylvania, 3500k white light
    Philips or Sylvania, 6500k Daylight tubes

    If it make any difference to what will be the best option I will be using a soil based substrate and am 50/50 on using presurised co2.
     
  2. Tom Barr

    Tom Barr Founder
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    Kelvin temps are the basis for our color perception, not the growth of plants.

    A mix of higher K and mid K levels are nice for most folk's color opinions, but that's just how things appear to us, there's no real Kelvin plant growth basis.
    Even if someone manged to correlate them some how, I'd still suggest not worrying/learning about that aspect.

    Regards,
    Tom Barr
     
  3. Rohape

    Rohape Junior Poster

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    Not to debunk or question anyone, just my research. I read a book, which included tests done with a variety of lights. It concluded that plants actually absorb more green/yellow light. It also had tests on oxygen levels induced by different "K" lights. Conclusion was surprisingly "Cool White", or around 4000K.
    Here is a link of Kelvin degrees and spectrums.
    Excella, Full Spectrum Fluorescent Lamps, Full Spectrum Bulbs

    If you are still on the lookout for lights, I suggest this place. I was able to buy
    80W PC straight pin 4100K. I had NEVER seen these. I have them and they are working beautifully!
    Atlanta Light Bulbs, Inc.

    Good Luck!!
     
  4. Tom Barr

    Tom Barr Founder
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    But..........the bulbs and O2 have nothing to do with color Kelvin temps, that never addressed the question. They showed the full spectral curves, which can give you any idea, however, color temp is not defined by O2 production by plants nor are lux: PAR units are.

    Color temperature - Wikipedia, the free encyclopedia

    For exmaple, you can have a terrible ugly color temp and decent plant growth(like the cool whites), and you can have nice color and good growth with a 6700K, or an 8800K bulb.

    Collr temps are just integrated over the entire range of the spectrum, it does not tell you if the range in the spectrum is optimal for plant growth.

    If you believe that, then look no further than the blue Atinic bulbs used in reefs.
    They have a strong spike in the blue, but not much else.
    An ADA 8800K or 10,000K color bulb is higher, thus according the charts, it should be bluer, but it's not as anyone that's looked at the both will quickly see.
    The 10,000 or 8800 Bulbs will grow plants better and look better as well.

    The strong blue is balanced with some red but with less yellow etc.

    Ivo Busko's article is about as in depth's as anyone's on the topic.

    Regards,
    Tom Barr
     
  5. Afroturf

    Afroturf Junior Poster

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    Cheers for the input guys. From what i've read and the general consensus is that the best k rating for plants would be 6500-8000k and if i was to be doing a different type of tank i would choose something in this range with out any thought, but as i feel that the strength of the light that i use will be key in the tanks overall successfulness, I will not be using all 6500-8000k bulbs.

    As the bulbs don't cost to much i will buy 2 4000k bulbs and 1 6500k bulb. And see if 2 x 4000k or 1 x 4000k + 1 x 6500k look better.

    Would it be worthwhile swaping the old T8 aqua glo tube i've got for a Grow lux tube?
     
  6. Rohape

    Rohape Junior Poster

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    I think what I wrote could have been written better...what was in my mind wasn't properly conveyed in my post. And I'll probably make this more confusing than anything, and for the sake of learning and possibly debate.
    The following is as close as I can get to what I was "thinking".

    "Cool White" bulbs' color spectrum produce/eminate more of the colors absorbed by plants compared to other ranges of bulbs/kelvins tested. The basis for this statement/result was using the measured O2 output, reasoning more photosynthesis. (The only other bulb that had better/more results was I believe "Grow Lux").

    Did I do better? :D

    I agree, it seems the opposite. O2 production is defined or increased by color temp.
     
  7. Tom Barr

    Tom Barr Founder
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    Yea, I knew you knew :D

    Cool whites did the same in a research test for plants as any other bulbs.
    But that is in terms of growth, not our eye's preferences.

    I hate all those silly light units:mad:

    Regards,
    Tom Barr
     
  8. yme

    yme Lifetime Charter Member
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    just go for the philips 830/840/865. Pick a combination which pleases your eyes and watch the plants grow :D . All these T8 tubes are excellent for growing plants. Do not use grow lux and other fancy tubes. grow lux has a very low light output and needs to be replaced every year or so. The philips T8's will emit 90% (more or less) of it's original intensity.

    greets,

    yme
     
  9. Rohape

    Rohape Junior Poster

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    No No! Let's get way too technical and overwhelming!! :D
    Have fun with your new lights, it's always fun seeing your tank in a different "light". :p

    I totally agree. Such a hassle just for a light bulb! Thank god we don't have to make these choices on the bulbs in our house! :)
     
  10. naman

    naman Prolific Poster

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    pffff...
    Ivo Busko's paper says everything.
    Please your eyes (with interpet T5 HO Daylight Plus or T5 HO JBL Ultra Solar Natur), plants will adapt as for nutrients level.
    Red/blue lights (Sylvania GroLux, Plant Grow, etc) only stagnate plants.
    Detlef has tests on ADA lamps and JBL, Ivo 's don't.
    BTW - JBL's Ultra lamps has similar to those "wide spectrum" lamps spectra as LifeLite (Germany). The last have T5 HO, as spiral compacts too. Price is high -$30 per lamp, while for 20000 houres is ok as comparable to MH HQI, wich you have to raplace every year for so for 50-90$.
     
  11. Tom Barr

    Tom Barr Founder
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    You do not have to replace HQI nor standard MH's every year, perhaps if you have SPs corals, 12-18 months is good there.

    But I routinely replacement the ones I have about 2-4 years ranges without issue.
    They also run 25$ ea if you buy 10 at a time for 5000/10000K range.

    I think T5's really are good, they have the right amount of light and are good as far as spread.

    Their cost has dropped a lot in the last 1-2 years also and will drop further, as will HQI.



    Regards,
    Tom Barr
     
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