Thank you, Lynn. I really like the poly batting. It looks like it really keeps the substrate from slipping through into the water table. I'm going to get some and redo my tank. I went out today and bought some weed blocker liner for a new barrier because I do not like the one Joshs frogs sent. I would rather have one complete piece. You're right though, I wont be happy until I redo this. It's going to be a pain to separate any dirt from the drainage layer that falls in but I'm going to scoop most of it out before I pull out the barrier.