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PAR across the world

Discussion in 'Lighting' started by Gerryd, Jul 19, 2010.

  1. jcardona1

    jcardona1 Junior Poster

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    yes! those are great, i love them. Makes adjusting the height of your fixture very easy. I got them from Catalina Aquarium for about $7

    View attachment 1642

    DSC_2205..jpg
     
  2. dutchy

    dutchy Plant Guru Team
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    Today I came home and found out that one of my Aqualight T5 lights wasn't working. So I went to the LFS to buy a new one, and I bought an Aqua Medic. When I installed it, it seemed to be brighter, although both were 10.000K. I got my PAR out and measured at a fixed distance. I was very surprised that the AquaMedic put out 30% more PAR. I checked with a new Aqualight and that gave me the same PAR as the old Aqualight tubes.

    The conclusion is that lamp with the same Kelvin number but different in brand can give a 30% difference in PAR. That's a lot and doesn't make it easier to make any kind of calculator or graph.

    Just FYI,

    regards,
    dutchy
     
  3. pat w

    pat w Member

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    I guess that means if you don't have ready access to a PAR meter it's best to stick with one brand of bulbs. I don't like the sound of that at all. Sorta limits our options.

    Or shell out the $$$ for the meter.

    I wonder if there would be a coralation between Lux and PAR for a given Kelvin or if it would be variable based on the actual freq. spread used by a particular mfg. for that Kelvin.

    eg. for xx K and yy PAR == zz LUX?

    Pat
     
  4. nipat

    nipat Guru Class Expert

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    Can't. Because Kelvin is more about the color of light appearing to our vision.
    Different mixes of wavelengths can give the same Kelvin.
    PAR is based on wavelength. So, it can't be calculated from luminance and Kelvin.
     
  5. pat w

    pat w Member

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    Guess I'll just have to hope Catalina Aquariums stays in business till I have the $$$ for a PAR meter.

    Pat
     
  6. shoggoth43

    shoggoth43 Lifetime Charter Member
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    Hmmm....

    Glad I got the 4 bulb fixture and bought all the lamps for it then. I only use 2 at a time so I should be good for a couple of years. Maybe by then they'll state what kind of PAR the bulb will give. Probably not though.

    -
    S


     
  7. pat w

    pat w Member

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    Got the four bulb unit and only using 2 as well, so I guess we both have time to save up.

    Pat
     
  8. pat w

    pat w Member

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    I took VaughnH's Par chart and did my best to pull accurate numbers from it. I went to ZunZun.com and pluged the data into a cubic curve fitting program and then set up a spreadsheet based on the coefficients it gave me. Turned out like this.

    [​IMG]

    I'll be checking it for accuracy as soon as the survey begins.

    FWIW

    Pat
     
  9. ShadowMac

    ShadowMac Lifetime Members
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    I would be very willing to participate. I have been trying to figure out a way to measure PAR and really can't spring for a meter. Please PM me if this can be arranged. I would be more than happy to pay for all shipping and insurance.

    secondly..a meter measuring LUX is fairly affordable. What is the difference and can LUX be converted to PAR or compared in some way? Too bad bulbs or fixtures don't supply some sort of PAR info. You would think that a chart with various distances (unobstructed) from the fixture through water could be standardized with a product. Would vary between products, but a fixture from company X with company X's bulbs could provide a PAR measure of that setup.

    thanks
     
    #49 ShadowMac, Sep 2, 2010
    Last edited by a moderator: Sep 2, 2010
  10. Oreo

    Oreo Guru Class Expert

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    Lux can't be converted to PAR, just the same as one bulb can very by 30% from different manufacturers.

    A better question would be if a digital camera could be used to measure PAR. Since a digital camera can measure photo-spectrum and display that in programs like photoshop or GIMP, it would seem that there ought to be a way to use that spectrum analysis to calculate PAR. I'm thinking of something like a simple Adobe plug-in for photoshop. The idea would be to point the light fixture directly at the camera, at the preferred distance & take a picture of the bulb. If the camera isn't fast enough a lens filter could be used. All those things would need to be accounted for in the PAR calculation though- exposure settings, lens filters, etc.
     
  11. aquabillpers

    aquabillpers Lifetime Charter Member
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    Yes there is, for daylight, full spectrum tubes only.

    To convert PAR to Lux, multiply PAR by 54.

    To convert Lux to PAR, divide Lux by 54.

    Again, this works for daylight, full spectrum tubes only.

    Bill
     
  12. pat w

    pat w Member

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    The problem is when you buy your lights from a bargan house like I did the most you get is kelvin and the wattage. In my case T5 54w 6500K with no spectrum or other info. I've asked, they said they'd put it up on their website ... No go.

    Ya gits what ya pays for.

    Pat
     
  13. SuperColey1

    SuperColey1 Guru Class Expert

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    Are you sure that is right? The other day I read a post saying that a tube of identical W and K of another brand was 30% more PAR. How do we know the same cannot be said for daylight full spectrum tubes?

    Also each manufacturer seems to have a different perception of 'daylight' ranging between 5500K and 8000K

    From my knowledge I seem to recollect that daylight is around the 5700K area!! The majority of daulight sold are in the 6400-6700K range.

    AC
     
  14. Gerryd

    Gerryd Plant Guru Team
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    Hi all,

    Sorry to hijack the thread but I actually have an update :)

    Personal and professional life are rapidly changing around me and posting has not been a top priority...

    So, I DID take some pics/video of the PAR meter and I have a list of folks to send it to. I am missing some later volunteer's info and will correct that via PM.

    I was going to go geographically, but thought that if a tester had MULTIPLE tanks or combinations to test, then that would weigh more in their favor. So let me know so I can get it out..... More details to follow...

    First some pics/video of the meter:

    Please note that the LOW battery indicator is ON. At least I assume that is what it is. I no longer have the owner's manual and the one I find online does not mention it. So any insight is appreciated.

    http://www.apogeeinstruments.com/pdf_files/QMSS.pdf

    I will reach out to Apogee during the week re: the indicator and what to do. I am hoping I can swap a new battery prior to sending it out :)

    I also note that this meter is now >2-3(?) years old and has been replaced by a newer model.

    http://www.apogeeinstruments.com/quantum/index.html

    Please also note the separation of the cable housing from the unit. I also note the ground portion of the cable is outside the covering.

    These can be seen plainly in the last picture.

    The unit has been like this since I got it with no apparent ill effects.

    So some pics while the video is uploading with more to come:

    View attachment 1679 View attachment 1680 View attachment 1681 View attachment 1684 View attachment 1685

    I will post more of the different sides of the unit, but I feel it is in good shape other than noted above.

    Vid:

    http://www.youtube.com/watch?v=q5SjzLHgE4Q

    1). Please note the complicated ON/OFF mechanism lol
    2). The sensor is equipped with the mounting plate. There is a level within the plate. Note that this should be level when recording readings.
    3). The readings will change with even SLIGHT movements of the sensor as you can see with the video. It is very responsive IMO.
    4). Please use the green sensor cap when not in use :)

    The sensor MUST BE SUBMERGED for correct readings.

    Not much to it. Turn it ON, place the sensor where you want to take the reading, and have at it. Try to keep the sensor as level as possible for best results.

    I had to measure my substrate readings PRIOR to the 049 carpet, as it will no longer lay flat on it :) So, you may need to get wet...

    More coming in a bit..
     
    #54 Gerryd, Sep 3, 2010
    Last edited by a moderator: Sep 4, 2010
  15. aquabillpers

    aquabillpers Lifetime Charter Member
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    Here's a link to a discussion of the Lux-to-PAR conversion: http://www.advancedaquarist.com/2008/2/review Included there is a list of the relative ratings of various tubes.

    I asume that name brand bulbs (such as GE or Phillips) with Kelvin around 5500 (and maybe a CRI of 90 or more) would qualify as "sunshine" or "daylight" as far as this conversion factor is concerned.

    The results of this study will be so useful in answering this kind of question, and many others.

    Bill
     
  16. yme

    yme Lifetime Charter Member
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    it is :)

    just replace the batery.

    greets,

    yme
     
  17. evandro.carrenho

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    Does aquarium branded t5 ho bulbs really have any advantage over standard t5 ho bulbs, i.e. is it worth the price a aquarium branded bulb?
     
  18. SuperColey1

    SuperColey1 Guru Class Expert

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    Reef tanks - yes, planted tanks - No.

    You would be better off buying 3 x standard T5s than 2 x T5HO as you will get better spread for about the same wattage.

    In reef the advantage with T5HO is more light in smaller area so they can pack more in.

    We don't need that kind of light so we would prefer the light spread out more. More tubes/light sources gives more ability to spread.

    AC
     
  19. evandro.carrenho

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    2:20 AM
    Thanks for the answer.

    I have t5ho ballasts, have been reading here and there that t5no bulbs would also work on t5ho ballasts, but some say that bulb lifespan may decrease, other say bulbs may not turn on. Any inputs on that issue?
     
    #59 evandro.carrenho, Sep 6, 2010
    Last edited: Sep 6, 2010
  20. SuperColey1

    SuperColey1 Guru Class Expert

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    Check the datasheet that came with the ballast. May even have the tube options printed on the ballast

    AC
     
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