Here's info on how to change your substrate...
And why not change the rock work around? Do you have any pictures on how its currently set up??? It'd give the fish a change of secenry.
Marlin: Okay, a mollusk walks up to this sea cucumber, well he doesn't actually walk, he's just there, and he turns to the sea cucumber, and... Well, wait, there's a mollusk and a sea cucumber and...
Chum: You know for a clown fish, he's not that funny.