Mylar as reflective material?

Hi everyone,
before i set up my new 55g tank i want to get everything togther for it. I've purchased two 175 halide ballast as suggested by many for the lighting system. This whole system, including the canopy, is going to be a DIY project, so i'm going the cheapest way possible. Now comes the problem of the reflective material. Polished aluminum is surprisingly expensive and hard to get. For a single bulb the cheapest i've seen is $20. So does anyone know how well Mylar works. It says it reflects up to 98% of the light, but i'm just not sure how high the heat rating is on it? anyone know? What about just a plane mirror mounted above the bulb...does a mirror have a heat rating?
The last option is a gloss white paint, but like i said i'd hope that was the last option. Any help would be appreciated.

 

I don't know the heat rating of a mirror or mylar. (The heat issue would worry me about the mylar as well as the difficulty of getting it shaped correctly as there is substantial difference in quality on store bought reflectors). Here's an interesting link. http://aquarium.union.rpi.edu/articles/DIY_MH.html

 

I used three pieces of regular mirror cut to the right shape and mounted the bulb about 2" away from the mirror reflector. I put fans on all my lights so it does not raise the temp of the water to much.

The only place i use mylar is for fluorescent bulbs because there is not nearly as much heat

Peter

 

$7 solution

go to walmart and get some stainless steel polished mixing bowls (make sure you can see yourself in them, the clearer image the better) pick the 13" size at least. heres the secret take a hammer and pound 3"-4" dimpolls from the outside in, leave bottom flat. Stager 7 dimpolls but leave one space flat, in the space you left, cut out a slot the bulb will fit through. mounting them is up to you remember screws transfer heat, and will get very hot. Notes :center the bowl to the center of the bulb and adjust the hieght from the bowl bottom to the bulb to change the width of beam. you must dimpoll the bowl or it will become a spotlight. I found thesse to be better than the expensive one and won't cut you arm if you run into them.