Okay. I am wanting to build a fiddler habitat. I've been looking at some pictures and plans online and i have a question. You see some have the sand piled up on one side and the brackish water on the other and some have a wall between formed of rocks and silicone or glass and silicone or whatever. Would it be better to go with the wall or without the wall? cause i think that sand is probably gonna need some moisture so they can form there boroughs but i don't know maybe the wet sand could grow harmful bacteria? Should i maybe build a wall with a slat opening at the bottom so water can flow in? I could put some gravel in the bottom so the water can flow in better then cover the gravel with the sand? What should i do?