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Thread: kelvin rating vs colour spectrum ANSWERED!

  1. #16
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    Quote Originally Posted by shake View Post
    Also PiL I have some T8 tubes I bought from Bunnings that are Quadphosphor (I am assuming there are 4 different phosphor coatings). What would the 4th coating be ?
    Quote Originally Posted by shake View Post
    NEC I think MrFish. What ever Bunnings carry, and apparently 30% brighter than triphosphor.
    we went to bunnings today, picked up a quad phosphor light for the laundry, it is one of those circular tube ones, and claims to be 18% brighter. There is a noticeable difference it's definetly brighter.
    He's not the messiah, he's a very naughty boy!

  2. #17
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    aahhh... why indeed are we hell bent on kelvin
    i too asked the lfs from which i bought my lighting the same thing. and whilst browsing for lights also found a couple of articles that supported his theory...
    apparenly it's a marketing ploy that companies have introduced and obviously has worked. names like "cool white" and "warm white" go hand in hand with the kelvin labelling system. that's all i can suggest really... that and the confusion between kelvin and spectrum.
    i know that aquarium specific tubes (like the range of philips brand) have the kelvin as well as spectrum graph clearly on the packaging so that you can make an informative choice.



    lumens and lux i know nothing about, it's really scientific stuff though and i think it also has to do with intensity at the source as well as at distance from the light source. :?
    found a site that explains the scientifics of it all:

    http://www.ledtronics.com/pages/tech4.htm

    in aquaria, my belief is that it's not an exact science. what works for some doesnt for others and then you got that whole balance with ferts etc...
    light wattage is enough of an indicator for me
    [sigpic][/sigpic]
    We do not inherit the Earth from our Ancestors,
    We borrow it from our Children.

  3. #18
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    Well I'd say that we are not the ones that are confused....I mean, how many T8 light tube varieties can you think of that are being used in aquariums? I reckon it is all the light tube manufacturers that are the ones confused....
    And they are just trying to make our lives difficult and confusing. It's a conspiracy I tell you....

    Thanks for you advice PiL.

    Cheers,
    Oliver

  4. #19
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    Have a look on the NEC site, they have all the color charts for thier fluorescent light. Their Triphosphors seem to cover the base very well in regard to the usable color spectrums, although the Quadphosphors do not seem nearly as good, they have large spikes of usable color but very jagged color graph


    Ben

  5. #20
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    Ok, I'm pretty confused after reading all that. I am a simple man!

    So, to summarise, what should we be looking for in a fluroescent tube?

    It should be triphosphor, kelvin rating doesn't matter.

    What colour spectrum should we be looking for? Is it a matter of looking at the wavelengths?

  6. #21
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    Quote Originally Posted by Mr_docfish View Post
    Problem I have is that I was told that Lumens is a measure of light intensity within the 'visible' spectrum of the human eye. So would this be relevant to plants?
    Hey Doc,

    Yes, you're right - lux is a measure of the intensity that the human eye can see. The measure of intensity that is more relevant to plants is PAR or Photosynthetic Active Radiation (also known as Photosythetic Photon Flux or PPF). PAR takes into account the wavelengths that we can't see but which plants can use. The amount of light that a lux meter won't pick up but that plants can use differs between bulbs (because different bulbs have different colour spectrums). For cool white fluoros the error in a lux meter is up to 45% but in a metal halide is typically around 15%. The only reason I can think of that everyone talks in lux is because you can buy a lux meter for about $20, but a PAR meter will cost you 1000's??

    Cheers

    Gavin
    Last edited by partrg; 14-05-08 at 10:15 PM.

  7. #22
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    Can you lend me a PAR meter????

  8. #23
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    I'm a tight-arse so I've only got a lux meter!! Next week I'm borrowing an underwater PAR meter and also an underwater 'spectroradiometer', which measures the change in light wavelength with depth. (and no you can't borrow them )

  9. #24
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    What beer do you drink????
    What are you doing tomorrow night????

    What do you need for a little try....




    Oliver

  10. #25
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    You seem pretty desperate. I could do with a new kidney

  11. #26
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    Quote Originally Posted by Conway View Post
    Ok, I'm pretty confused after reading all that. I am a simple man!

    So, to summarise, what should we be looking for in a fluroescent tube?

    It should be triphosphor, kelvin rating doesn't matter.

    What colour spectrum should we be looking for? Is it a matter of looking at the wavelengths?
    here is your light tube:
    http://www.lyco.co.uk/products/G-E--...htm?prodID=479

    manufacturer has not added any further info... and i assume the packaging doesnt say anything either. dont worry though, most triphosphors are suitable since they peak in all the spectrums that we require.
    i'd be more inclined thinking about wattage/brightness for luxuriant plant growth.
    [sigpic][/sigpic]
    We do not inherit the Earth from our Ancestors,
    We borrow it from our Children.

  12. #27
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    Quote Originally Posted by Jezza View Post
    good info - explains alot

    does anyone know what the spectrum is of MH bulbs?
    i know many people use them (including myself) so they must be good, but i'm wondering if they have a 'better' or 'worse' spectrum than fluros in regards to plant needs.
    Hey Jezza,

    This is the spectrum of the metal halide lamp I used to use; it's a 150 W Osram 5200K. I'm now using the 8000K watergrass lamps which I haven't seen a spectrum for.




    Metal halides use a mixture of gases to get the required colour temp and not phosphors like fluoro tubes. You therefore don't get the spikes in wavelength corresponding to the phosphors. The spectrum though contains all the right wavelengths for plant growth, as well as many others.

    Cheers

    Gavin

  13. #28
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    Is that the Osram 150w (double ended) "NDL" ?

  14. #29
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    Close, it's double ended but is the "D". Here's the NDL. Not much difference hey




    Gav

  15. #30
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    Here's a link that might be helpful.
    Thought this would be the most appropriate place for it.
    http://www.nelt.co.jp/english/products/index.html
    B.

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