Construct a formal garden pond

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Why construct a formal garden pond:

A raised formal pond - wholly or partially above ground.

  • Suitable as focal points with pond plants or fish ponds.
  • Useful for elderly or disabled to work in more easily.
  • Less dangerous for children.
  • They are not easy for amphibians to climb in and out of so only suitable for airborne wildlife.

A below ground but formally shaped pond.

  • Suitable as planted ponds, fish ponds or wildlife ponds (if the edging is made wildlife friendly.)

How to construct a raised formal garden pond:

  1. Design the shape & size:

    as outlined in Pond design - shape & size.

       2. Dig out the pond profile:

as outlined in Build a pond by digging - work from the outside edge of the formal pond and dig the shelf areas and the deeper water areas.

  • Koi fish ponds have special requirements - deeper 80-120cm(3-4ft) deep dependent on fish sizes and with specialist filters
  • Other formal ponds for goldfish and plants can be made to a total depth of 60 - 75cm(2ft - 2ft 6")
  • Create shelf areas at depths of 15cm and 30cm (6"and 12") below finished water height for plants either in the corners or along 3 of the edges.
  • Make the shelves cover only one quarter of the surface area.
  • Formal garden ponds tend to have more deep water waterlilies and less marginal plants.
  • To safely add plants to a koi pond - add a wide shelf area with a barrier of brickwork wall on the deep water edge of the shelf that allows small fish and water to flow through but keeps the larger fish away from the aquatic water plant baskets.

      3. Work on the blockwork construction:

  • Dig a shelf to sink foundations and the first block below the garden level of soil.
  • It is important to ensure this foundation shelf is level or any further building above it will not be level.
  • Build upwards in grey blockwork.
  • Build face brick to match the garden around the outside skin of blockwork.
  • The face bricks should extend one brick higher than the grey blockwork.

      4. Lining the blockwork shape with flexible liner:

  • The rough blockwork should be covered by a geotextile membrane as underliner. See Lining the pond hole.
  • Fold it into corners and remove excess in the folds.
  • Choose and measure for your liner. See Lining the pond hole.
  • Lay the flexible liner over the underlining making sure it lays on the base of the pond and reaches all the corners
  • Start to add water to weigh the liner down.
  • Stop water filling and adjust the liner before too much weight is on it. Pull out the creases and try to put all the folds in the corners.
  • Continue adding water and check creases and folds
  • Be very careful with the corner folds checking that all edges of the liner are higher than the top of the outer face bricks.
  • Stop adding water before you reach the last block

      5. Finishing detail:

  • Put in pipework for filters or pumps making sure the pipe is as high as possible to the top of the face bricks.
  • You want the top of any pipe to be to the top of the face brick so water can fill well up the face of that outside brick.
  • Take the geotextile and the liner smoothly over the top of the lower inside blockwork level.
  • Stand it up vertically and fold it over the top of the outer face brick.
  • Build up the inside blockwork wall to the same height as the outside face brick wall using a face brick.
  • Mortar the outside decorative brick onto the liner in line with the blockwork inside edge.
  • When you look across the formal pond you see matching brick to the outside brickwork.
  • The liner stands up between the 2 lines of face brick and across the top of the outer facebrick.
  • Complete the build with a coping stone or slab mortared across the 2 lines of brick trapping the liner in place laying above the outer brickwork.
  • When all mortar is dry trim back the surplus liner by cutting away from under the coping stone.
  • The facing brick and mortar line will be under the water level.
  • Seal both with a waterproof sealant to prevent alkaline leaching. G4 is an example of sealant.
  • Raise the water level to its full height - half way up the inside facing brick.