Actually, it started out fairly even. I leveled it all out but they dug and made hills and burrows. They dug out the hydro balls as well once they reached the bottom. This summer I'm going to re do it with a layer of plastic cross-stitch screen on top of the hydro balls to prevent them from digging them out. Then put the eco earth on top of that. They carry out anything they don't want in their burrow and put it somewhere else lol! They keep it clean and remove any cricket parts or debris.

Once I realized they were doing this, I turned my thermostat controlling the under tank heat mat way down to prevent over heating them since I know at least one burrow goes down to the glass.