Mirror

[reefburnaby]

Hi,

IMHO, it really does matter if the light is distributed using a specular reflector or a diffusive reflector. The main idea is to get light from the bulb in to the tank and both do the job. You'll just have to design the reflector to do the job correctly. In other words, a specular reflector doesn't look exactly the same as a diffuse reflector.

So, in terms of white vs shiny, white and shiny do a very good job at reflecting visible light. The difference between white and shiny is that shiny reflects other types of waves (like gamma waves, x-rays, infra-red and etc) and white doesn't do a very good job at that -- hence white paint's high emmisitivity. Emmisitivity is a measure of how much electromagnetic waves a material will absorb -- visible lilght is only a small band in the electromagnetic spectrum. Since our application involves concentrating visible light in to our reefs, then shiny and white should preform similarly (with the upper hand to shiny...since 100% pure white and mirror flat surface is hard to obtain with paint).

Specular and diffuse refectors have their problems. Diffuse refectors tend to spread their light even across the reef -- this may be problematic if you are try to raise light loving corals. Specular reflectors tend to concentrate their light on to specific bands within the reef. IMHO, this can be problematic because certain parts of the reef aren't well lit and some are too well lit -- so coral placement will be key.

One point that I haven't seen in papers is that white reflectors do get hotter than shiny ones. This is because white does not reflect infra-red very well. This may be a good thing since we can remove the heat from the white reflector with fans. On the other hand, a shiny reflector would deflect the IR waves in to the water and warm it up. It is much more difficult to remove the heat from the water...

So...there's my take. Both methods are fine. The design of the reflector must take in to account of the advantages and disadvantages of each method.

Hope that helps.

- Victor.

[ 14 February 2002: Message edited by: reefburnaby ]

[ 14 February 2002: Message edited by: reefburnaby ]</p>