How to install preform ponds

Preformed fibreglass ponds

The alternative to working with a flexible liner is a preform fibreglass pond.

Check carefully before purchase for:

Shelf variety and the proportion of deep water to shallow shelf area
Choose a shelf layout that does not have a narrow shelf rim around a large expanse of deep water. This is the wrong proportions for a natural looking wildlife pond
Always measure your chosen space before going to the Garden Centre. It is easy to be misled looking at an empty pond out of situ.
Choose the largest pond your space will allow

Often more tricky than you thought
Mark out the profile of the pond and its shelves on the ground using a series of hose pipes or string
Dig a little larger but as near as possible to the correct shape so that the preform sits snugly in the hole
Protect the pond from sharp stones with a layer of geotextile in the hole
Bed the pond into the hole so that it is level
Start to fill with water and place a spirit level over the top edge
As the water starts to weigh down the pond correct the level if necessary while backfilling the space around the preform shape with sand

Preform ponds can work well if placed inside a raised pond surround of concrete blocks

Hide the horizontal rim between 2 brick layers
Preform ponds have a horizontal rim around the top which is hard /impossible to hide or camouflage into the rest of the garden
Water can only fill to just below that rounded top edge or the water will flow away
There is no way of creating a vertical upstand as we have recommended with the informal and formal constructions
The only way to hide that rim is with slightly overhanging stones or coping slabs dependant on your style of pond