Line the concrete and you'll be fine. I had a number of CPs in a bog garden that lime was added to and they all eventually died, so yes the concrete will impact the plants eventually. Rain water is naturally acidic and that will break down the concrete enough that it will cause a problem.

Sounds like a great idea as long as you use a good liner!

by the way, love your chosen gardenweb name. I'd love to see a real live sphenodon!

Thanks a lot fred! Now I know what to do.

I am pretty new to CPs but I have another container bog garden with Thalia dealbata, Cyperus papyrus, Eichhornia crassipes and some other bog plants. They all do very well as the temp here in Asia doesn't really go below 10c in winter.

I've only seen a live tuatara once in a zoo in New Zealand:) It's an amazing little creature!