# Mirror as a light reflector?



## YankyTexan (Mar 8, 2008)

*APPLICATION:* I have constructed a canopy with six F15W-T8 bulbs. The bulbs are arranged in a parallel fashion occupying approximately 18"W x 14"D area. The ballasts are remotely located to dissapate any excess heat generated. Currently the interior of the canopy is painted with a white appliance enamel.

*SOLUTION:* I am considering utilizing a mirror (17"W x 15"D) attached to the lid to help reflect light towards the surface of the water. While the mirror is not the correct shape it has to be better than a white enamel surface at reflecting light?

Does this seem like it would be worth the effort? Am I missing something?

Thoughts, comments and/or observations are welcomed.


----------



## BiscuitSlayer (Apr 1, 2005)

Got any pics? It might help to visualize what you are saying better.


----------



## Harry Muscle (Mar 13, 2007)

When I contemplated building my own hood I was planning on doing exactly what you describe. It's not the best shape (ie: flat), but if all you have is a flat white reflector right now it's a pretty good upgrade.

Thanks,
Harry


----------



## YankyTexan (Mar 8, 2008)

The mirror would be placed between the tombstones (they hold each end of the lightbulbs) to the underside of the lid parallel to the surface of the water. Thus the light from the top of the bulb (away from the water surface) would reflect from the mirror (somewhere, I'm not really sure where!).

Thanks,
Daniel


----------



## Wasserpest (Jun 12, 2003)

YankyTexan said:


> While the mirror is not the correct shape it has to be better than a white enamel surface at reflecting light?
> 
> Does this seem like it would be worth the effort? Am I missing something?


White color is amazingly good for this purpose. If you don't use a parabolic shape I would think that white color would be superior to a flat mirror.


----------



## Harry Muscle (Mar 13, 2007)

How could white color be better than a mirror at reflecting the light back down?

Harry


----------



## Ransom (Mar 3, 2006)

With a flat mirror, the light rays are reflected like billiard balls. The only ones that will be reflected straight down are the ones coming straight up from the bulb. When those are reflected back down, they restrike the bulbs and don't go into the tank. The light hitting the mirror at an angle is reflected at an opposite angle and mostly goes out the side of the tank or hits the sides of the hood/canopy. If the sides of the hood/canopy aren't reflective, they absorb the light reflected at an angle from the top and also the light that comes from the side of the bulb.

If you paint it bright white, the light is scattered in all directions instead of being directly reflected so some of the straight-up light goes sideways, hits the bright white sides of the canopy and some of that gets scattered down. Also, some of the light from the side of the bulb gets scattered down.

Over all, more light gets scattered down by white paint than would be reflected down by a flat mirror.


----------



## YankyTexan (Mar 8, 2008)

Thank you to all who contributed. Ransom you make a compelling arguement. I might modify my original idea and place 3 rectangular shaped mirrors on on the inside (front, left & right) of the canopy in addition to the one attached to the underside of the lid. Now you'd have some angles of reflection going on in that canopy. Besides, if the fish became bored they could look at themselves.

thanks,
Daniel


----------



## Wasserpest (Jun 12, 2003)

Harry Muscle said:


> How could white color be better than a mirror at reflecting the light back down?


It doesn't seem logical, but with mirrors being good reflectors, but bad diffusers, the flat arrangement leads to a lot of restrike (light being bounced back from the mirror but blocked by the bulb itself.

White is a better diffuser, and with the bulbs close to each other, I would expect more light to go into the tank than with the flat mirror.

I built my share of canopies with mirror reflectors, and all I can say is that it doesn't seem to make sense, but if you actually compare flat mirror to flat white, you will see... the light. 

Edit -- I am a slow typer. Like Ransom said...


----------



## ColeMan (Mar 9, 2008)

it's my understanding that mirrors are also inferior reflectors due to the fact that the light has to go through the glass, then hit the silver, and then bounce back out through the glass _again_- the light is passing through the glass twice...we all know about the impact (albeit not too pronounced) that glass aquarium hoods have on lighting, so it stands to reason there would indeed be light loss...i'm sure there's another material...let's think really hard...


----------



## distrbd (Feb 17, 2006)

ColeMan said:


> it's my understanding that mirrors are also inferior reflectors due to the fact that the light has to go through the glass, then hit the silver, and then bounce back out through the glass _again_- the light is passing through the glass twice...we all know about the impact (albeit not too pronounced) that glass aquarium hoods have on lighting, so it stands to reason there would indeed be light loss...i'm sure there's another material...let's think really hard...


Well said.
I would consider thick Maylar.


----------



## markalot (Apr 8, 2007)

Hi,

newbie to lights and reflectors.

I have polished aluminum reflectors (mirror like) I added to some old incandescent fixtures (using CF). They are bent to reflect the light at different angles. The way I see it if you look at the the fixture from different angles and can see the bulb then you are getting a good amount of light at that angle.

Watch your eyes here, I blinded myself taking this  I took this picture at an angle to show the reflections.










Now if you had a simple mirror in back you would get decent side to side coverage but very little front to back. I can tell you that since adding these reflectors last week the front of the tank, where this light sits, is much brighter.

I'm still seeing spots.


----------



## BiscuitSlayer (Apr 1, 2005)

You could build reflectors out of wood and mirrors that were cut appropriately. Just make the angles out of strips of wood and then glue the cut mirror pieces to fit on the angles like this:

\_/

I would think that if you did it properly it would be a lot better than using just a flat mirror behind the bulb.

Another option is to use reflectors similar to markalot's post. There are a number of places where you can get the polished aluminum reflectors as he suggested. 

What are the lengths of the T8 bulbs your using?


----------



## ColeMan (Mar 9, 2008)

sure he could build reflectors out of mirrors and wood, but why waste the time...i think mylar would be better here for sure, for a number of reasons. It's cheaper, there's less light loss, it's easier work with and more versatile...don't you think?


----------



## lauraleellbp (Feb 3, 2008)

If you're going to build your own, and just don't want to use Mylar, then you should take a look at the configuration of the reflectors on www.AHSupply.com fixtures.


----------

