The LFS usually has a selection of slate, but you know it costs. So I made a visit to the Lowe's (home improvement superstore) one day and checked out the slate tile section. Wow! A wide variety to choose from, and best of all, $1.99 a piece for a whole tile.
I brought a couple pieces home, layed them on a towel over a rug and gave 'em a couple of whacks with the hammer. Viola! Instant decorations. I ended up with a variety of sizes and thicknesses. Of course I washed the stuff off the back first and then boiled them for a bit before arranging them in the tank.
Here are a couple of pics. I already had the two end supports in the tank, but a piece of rainbow rock was setting across them.
