all my ponds have rug padding under the liner. padding is 100% synthetic
and doesnt rot. it is cheap to buy (used may have hidden staples which
would punture the liner). I tried the "old rug" and when we removed the
liner after a month is was all moldy and rotted and we found more staples.
Most important. padding bends easily to fit the contours of the pond, it is
light weight, it cuts like butter. rug is stiff, heavy.

I built 1.5 feet up from the ground using a stud wall and outdoor plywood.
is easy and cheap to do. Ingrid