Hi

We have just moved into a house with an existing pond. The pond has been
made using a some form of liner, but from the feel, ie I can easily push a
'dent' in base of liner so I don't think the original builder has put sand
underneath to support it.

I would like to add some rocks so that there is a rockery effect coming from
the pond, because of the way the pond has been done, the only way I can do
this is to put the rocks in the water on the liner. My worry is that the
rocks may eventually puncture the liner.

I was thinking of putting a sheet of polystyrene packing under the rocks to
protect the liner. Will anything leach out of the polystyrene that may harm
the wild life? The pond is teeming with wildlife in the form of frogs and
newts which I would like to encourage and protect.

Thanks for any help given

Dave