To protect the pond liner from any chance of being ripped or torn by anything sharp in the soil we used the old carpet that was left in the Bungalow when we moved in as a protection and a good one it was too, we pegged the carpet in place using degradable pegs you can get them from gardening stores or ebay they use them for the weed killing membrane rolls, anyway they worked a treat and held the carpet in place for the liner to go in.
