CD's? That's friggin' hilarious, dude! I love it... Not laughing at you, just struck me funny..
Be aware -- a lot of things that seem to concentrate light actually suck it up. Mirrors are a good example --- I suspect your CD's do the same.
You know, aluminum foil (backside toward the light, NOT the shiny side) makes a good poor-man reflector. I have my plants surrounded by cardboard panels covered with aluminum foil almost to the height of the light. The little gap is for safety -- don't want to start a dang fire. It really works -- my light meter proves it in no uncertain terms.