How to install preform ponds in your garden

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Preformed ponds in plastic or fibreglass:

A good alternative to working with flexible liner.

How do I choose a preformed pond liner?

  • Look at shelf variety and the proportion of deep water to shallow shelf area.
  • For a wildlife pond - Choose a shelf layout inside your preform pond that has wider shelves for plants and shelves at different depths.
  • More choice of shelf depths allows more varied planting to suit more types of wildlife creatures.
  • For a fish pond - Choose a preform shape with more deep area and less planting shelf.
  • Always measure your chosen space before going to the Garden Centre. It is easy to be misled by size when looking at an empty pond out of situ.
  • Choose the largest pond your space will allow.
  • Your fibreglass pond should have a lifetime guarantee if you fit it correctly.

Fitting rigid preform ponds into the ground:

  • Mark out the profile of the pond and its shelves on the ground using a series of hose pipes or string.
  • Measure the depth of each level.
  • Dig a hole a little larger but as near as possible to the correct shape so that the preform sits snugly in the hole.
  • Often more tricky than you think!

Underneath the preform pond:

  • Put a 5cm layer of damp sand in the hole to go under and around the preform pond.
  • Bed the pond well down into the sand so it is level.
  • Start to fill with water using a spirit level across the top edge.

As the water starts to weigh the pond down:

  • Correct the evenness of the pond
  • Water will always find level so use the spirit level and make sure the top rim of the pond is level.
  • Backfill the space around the preformed shape with more sand.

Preform ponds dug into the garden work well as wildlife ponds:

  • But the horizontal rim around the top of a preform is difficult to hide or camouflage into the garden.
  • Water can only fill to just below that rounded top edge or the water will flow away.
  • The only way to hide that rim is to securely fit slightly overhanging stones or coping slabs.

Or preform ponds can be raised up:

  • Preform ponds can also work well if placed inside a raised pond made of concrete blocks.
  • The horizontal rim can then be hidden under a securely fitted coping stone.
  • Raised ponds are not as good for amphibians as preform ponds sunk into the ground.
  • They are good for fish and plants if shelves are included to attract air borne wildlife.