Discussion in 'Planted Tank Equipment' started by Greystoke, Jul 27, 2010.
Deleted post. Please remove.
where are the half parabolic reflector designs?
mine looks kinda like this:
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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.
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?
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.
OK guys, just a little desert.
I worked out an Excel spreadsheet that will calculate the Efficiency of a Reflector with a single Tube
Try it out and let me know what you think.
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.
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.
This calculation does NOT include the reflection losses at the water surface.
Should I include that?
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.
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.
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...
That can be accurately calculated.
Light hitting the glass surface below the critical angle will be reflected. Now where are my notes . . . .
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