[akangelfood]

Another idea for covering holes is egg crate. I love the stuff! You can get it in a few different colors, mostly white and silver, at your local home and garden store (Lowes, Home Depot, etc). They're designed to cover florescent lights. They're cheap and easy to trim, just use a pair of snips. I'm generally hardware-challenged and did it with no problem. It's very easy to create holes where you need it, say for filters or heaters, and it'll rest right on the aquarium frame itself. Might look into that as a more permenant option than a sheet or foil.