I have about 5 inches of coconut fiber in their tank currently, with the reptile moss carpet on top of it. So they never come into contact with the fiber. I figured if I bury it way in there, it'll heat it up nicely but they won't ever be able to touch it I'm gonna experiment til I get it right. I hate coconut fiber too (reason the carpet is over it, lol.) But it works good as building up height to get in the water.