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.
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- Preformed ponds
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.