I have Pekin ducks, and am making a small pond for them to play in. Thought I had it done this weekend, I used 12mm thick plastic liner, but it sprung a leak from their little nails- it just slit it and drained the pool. Has anyone built a pond? ANd if so, what would you suggest for liner? The sides are fairly gradual so theoretically they should be able to walk out without needing to use their nails on it. I've thought about concreting it and sealing it, but wow, that's so much more involved I think! HELP!!!