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  1. #1
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    Interesting theory on "full" lighting in reefs...

    Here is an interesting thread about using the sides and other various surfaces to reflect the light. This might be of more interest to the SPS/light loving reefers.

    http://reefcentral.com/forums/showth...hreadid=480178

  2. #2
    liv
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    Former Moderator liv's Avatar
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    nice catch !

    moving.. so temporarily out of SW :b8:
    planning next tank, possibly 60x30x20 on 2x plasma.
    updated: 2011/05/30

  3. #3
    Senior Member ak_sniper's Avatar
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    Nice, my 175W lights up pretty bright my 20L but since I don't have a bought reflector but a DIY, maybe this could add some extra light, especially under the overhangs!! Plus im sure I can get a small mirror cheaper than a reflector!! Ill have to look into this one!!

    Thanks!!

    AK
    20G Reef Tank (Starting again...)

  4. #4
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    Verrrry interesting ... BUT the light is traveling through glass and we know what that dose to the lights quality. How is its quality affected by being reflected? Dose it change?
    Rob

  5. #5
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    Good questions OSD.

    Interesting find Toutouche

    The 49 degree angle must be critical because my understanding of a mirror surface is that it absorbs light.

    That is why mylar is so popular as a reflective material used in indoor vegy gardens.

    Very reflective but does NOT absorb light.

    Lou

  6. #6
    Senior Member Deafboy's Avatar
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    Toutouche,

    You mentioned in Reef Central that "UV gets cut" while going through glass. Well, this is generalized statement. In fact glass is still highly transmissive to UV between 340 and 400 nm. I've calculated the transmission of a sheet of regular float glass of 8 mm and 16 mm thickness. The results are shown below:

    300 nm 19% 4%
    320 nm 64 % 43%
    340 nm 89 % 82%
    360 nm 95 % 94%
    380 nm 95 % 94%
    400 nm 95 % 94%

    I've included the effects of reflection in the numbers above. Transmission in the visible range would be 96%.

    So even a double-pass of 340 nm UV light through a 8 mm thick mirror would leave 82% of the original power. In my opinion, the absorption is quite negligible even at 340 nm.

    Michel
    20 g reef, 72 g reef

  7. #7
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    Michel,
    But what happens above 400nm..., does it go to 100% or does it stop above 400? Actinic is 420nm.
    I have since found out that the mirror is temporary till he finds some polished aluminum or similar material. I have been thinking of using type of chromed metal to line my hood on my bigger tank.

  8. #8
    Senior Member Deafboy's Avatar
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    Originally posted by Toutouche
    Michel,
    But what happens above 400nm..., does it go to 100% or does it stop above 400? Actinic is 420nm.
    I have since found out that the mirror is temporary till he finds some polished aluminum or similar material. I have been thinking of using type of chromed metal to line my hood on my bigger tank.
    Above 400 nm is the visible range. Transmission is very high (96%) in regular glass in the visible spectrum. Most of the "losses" occur due to reflection at the air/glass boundary (4%).

    BTW, if you want to increase the amount of light reaching the aquarium with MH bulbs, you might consider using a reflector that is optimized for a point source. Most reflectors I've seen in canopies seem to be optimized for line sources (e.g. fluorescent bulbs). A round parabolic reflector would probably be a better choice.

    http://awi-industries.com/relectors.html

    I have an idea of modifying an Altman 360Q spotlight (ellipsoidal reflector with lens) to take an aquarium type MH bulb. In principle, I could do away with canopy altogether and precisely "project" the light to the tank from the ceiling or by reflecting the light off a mirror. Since the efficiency of these devices is quite high (something like 70%), I would expect a lot of light reaching the corals.

    http://www.altmanltg.com/prod_ellipsoidals/360Q.pdf



    Michel
    20 g reef, 72 g reef

  9. #9
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    cool.... this is some "intense" stuff.... lovin' it!
    Health Before All :wink5:

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