The efficiency of a Light Canopy

Discussion in 'Planted Tank Equipment' started by Greystoke, Jul 27, 2010.

  1. Greystoke
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    Deleted post. Please remove.
     
  2. Greystoke
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  3. wearsbunnyslippers
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    wearsbunnyslippers Administrator Staff Member

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    where are the half parabolic reflector designs?

    mine looks kinda like this:


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  4. Greystoke
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    Mathemathics are the same. Gate width and depth still apply, as - of course - height above water and cover (extent of the water surface)
    What cannot be established is the extent of "light squashing" inside the reflector. No info.
     
  5. f-fish+plants
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    f-fish+plants Aquascaper

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    Looking good Greystoke ... I am playing with submerging a portion of the tube in the water ... this has had a huge improvement in illumination of the substrate and some other side affects but those I can work on to practical solve.

    One of the things that I need to do now is rethink reflector since it will need to made of a material that has no aluminium or other nastiest that will leach into the water. A portion of the reflector will also be submerged with the light. My gut tells me that I should not submerge more than 50% of the tube cause then the efficiency of the light originating out of the water to the reflector is reduced - or do I just go with 100% submerging and deal only with one medium for the light to travel through - be it direct or reflected?

    Later Ferdie
     
  6. Greystoke
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    The water surface looked at from below is highly reflective, as I know from scuba diving. You can only see what's directly above you. Anything else is blocked by (internal) reflection.
    I think that all your tube needs is a flat reflective strip (white plastic?) placed right above it.

    Just don't ask me how effective that would be. [​IMG]
     
  7. Greystoke
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  8. tyronegenade
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    tyronegenade Specialist

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    Oh cool! I'm at about 61%! Does "alum tape" have the same reflector properties as tin/aluminium foil?

    Thanks for all the hard work.

    P.S. with the "white paint" option I'm at 85.3%, and now I get ~45 PAR at my target depth of 45 cm. Cool.
     
  9. Greystoke
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    I think the foil is much more reflective. WBS was talking about 92% for polished aluminium. I think foil falls in that category. I must include that. Meanwhile, you could temporary use the "white paint" choice.
    The Al tape I'm talking about refers to ordinary Al sheeting material. You find a lot of reflectors made of that.
     
  10. Greystoke
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    Uhhhh,
    This calculation does NOT include the reflection losses at the water surface.
    Should I include that?
     
  11. tyronegenade
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    tyronegenade Specialist

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    Cor, if your comment is directed at me, then I used a 20% reflection value in my model.

    Can you calculate reflection loss in yours? Anything more accurate than 20% would be much appreciated.
     
  12. Greystoke
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    No, I can't calculate that. Too many random values, such as ripples and movement. Like you, I take 20% loss as an average, but I better inform the members that the efficiency EXCLUDES the reflection loss before entering the water.

    Reflector Efficiencies
     
  13. tyronegenade
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    tyronegenade Specialist

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    Sorry to play voodoo-which doctor (sorry, "traditional healer") on this thread but I was wondering if anyone had any values for "reflection loss" when it comes to cover glasses over a tank. This seems to be the best thread to ask this question...

    Thanks
     
  14. Greystoke
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    That can be accurately calculated.
    Light hitting the glass surface below the critical angle will be reflected. Now where are my notes . . . .[​IMG]
     

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