I heard some people use PVC pipe pieces in order to create tunnels and caves for fish to hide in. What's the best way to go about cleaning them up real good so that I can put them in the fishtank?
I don't know the melting point of the plastic. Some plastics can take a high melting point and be boiled safely. If all else fails, scrub it with vineager or bleach. Just make sure you let it thorough dry if you do bleach it. Bleach evaporates and leaves nothing behind so it's safe to use after that but that's the tricky part, making sure it's totally dry.