Before shopping for a used fish pond, create a rough plan for where the pond will be and what will be around it. Measure this space to determine the largest possible fish pond. Preformed fish ponds are typically made of high-density polyethylene, a durable and safe plastic. Fiberglass ponds are also available but are more expensive and less natural-looking. Carefully inspect any used pond for damage or significant wear.
Most preformed fish ponds are safe for the majority of fish. However, the previous owner may have used a variety of cleaning solutions or treatments. Make sure to inquire about how the owner kept the pond and what types of fish inhabited it. Also, thoroughly rinse the fish pond before use.
Typically, preformed fish ponds are the only type available to buy used. In some cases, the materials from a liner fish pond may be available for sale. Buying these is similar to buying a preformed pond but the pond then requires some additional assembly to create a desired shape.
After purchasing a used fish pond, mark its outline in the ground using a series of pegs. Make the outline a few inches larger than the pond. Dig out this area to the depth of the fish pond. Add sand to the base level and any areas where raised shelves in the pond will be. Place the pond in the prepared hole, making sure it is level. Fill in any remaining gaps with sand and make sure to cover the edges of the pond with stones to protect them.