Hi all. I was wondering if any of you have ever experimented with pvc or some other "tube like" material to make tunnels or caves under your gravel. I was about to thow away some old clear plastic mustard bottles and decided to instead of go to lowes to buy some pvc I would use these. My plan is the cut the bottle lengthwise (like a halfmoon) and then cut a hole in the side of the piece that is left. Then silcone some matching gravel to the outside of the bottle. Let it dry out then bury the tube against the glass of the aquarium. My idea to to make a small undergravel cave that my raphael catfish and hid in at night. Then if I wanna see him I shine a flashlight up to the tank where the flat part of the halfmoon shape is resting against the glass. Any thought or experiances with this idea? Pics coming soon!