Posted: 18/03/2013 at 08:02
The main purpose of stones around a pond, and hard edging, is to hold down the edges of a liner.
With a pre-formed pond that shoud be not be necessary.
I like to have plenty of plants around the pond, so that small animals can get in and out in safely. If it's a preformed pond you could run grass right up to it.
If the pond is warping, then I suppose the best thing would be to find out why, and do something about the cause. Maybe some more support is needed beneath part of it. Or a little bit more soil needs to be taken out from somewhere.