I would go eggcrate over lexan with drilled holes. In another forum there was a much debated issue on what side of the egg crate issupposed to be up, and why.....supposedly someone did a light transmission study and found that if the narrow edges are up, it diffuses over 25% of light outwards (through the sides of the tank and not downwards into the tank......and if it was placed with the wider surfaces up it blcoked upwards of 20% of light, but it concentrated more of it in the tank.......There is supposedly some sort of ideal height above the eggcrate to place a light to elimiante a lot of these so called spread or reduced light problems, but I seriously doubt if its going to matter much with 99.99% of any aquariums out there.....Only thing they pretty well all agreed on was not to use the chrome plated eggcrate as it soon flakes off and winds up in the water.......They also have black egg crate in some stores as well......and it does not alter the so called light tests they did one bit a far as light transmission is concerned.....