Wildlife pond without liner
I've only joined this website today and already have a question for those of you who have got experience with building a wildlife pond. I garden on heavy clay and would like to build a small pond (approx. 1.5x2.5 sqm) next to a (still to be built) patio.
As space is at a premium and because I don't really like to look of heavy boulders weighing down the pond liner around the edges, I was wondering if anybody has ever tried just compacting clay and the filling the hole with water?
Also, I have read a bit on the internet, and apart from Butyl and PVC liners, there is something called Bentonite, which is a self-healing clay-based liner. Has anybody here ever tried to use these? I understand they are quite expensive. Would they save me from having to weigh down the liner and thus lose valuable space?
Sorry, I know I'm asking a lot of questions at the same time. Am hoping someone can help me with some of them.