Koi carp are often described as Living Jewels – and can bring a huge amount of pleasure to those who keep them. They thrive best in the cleanest and clearest water, they can grow very large and are known as prodigious waste producers. So the challenge when creating a new Koi pond is to manage these apparently competing demands. One of the best starting points is to design a pond that meets all the needs of KOI fish. Building a regular shaped pond and lining it with a box-welded pond liner is a good starting point.

The secret of a successful Koi pond is deep water – a minimum of 1.5m deep and ideally up to 2.0m – smooth sides and bottom to enable waste matter to naturally fall to a good filtration system and sufficient water volume for the number and size of fish.  As a rule of thumb, you should allow between 150 and 500 gallons of water for each Koi, but equally important, the filtration system should be capable of turning over the total water volume of the pond between eight and twelve times a day.

Butyl rubber and Epalyn (EPDM) rubber pond liners have been tried and tested with over fifty years of use and are proven material for use, not just in garden ponds, but in major water containment projects and large-scale landscaping.  Used traditionally, these pond liners are laid as a pre-fabricated single sheet into a traditional garden pond which has gently sloping sides and the inclusion of planting shelves.  While the materials are flexible and will stretch to cover the contours of the side and bottom of a pond, the end result inevitably has folds and creases which normally have no adverse affect on the end result.  But, when creating a Koi pond, the sides are usually constructed vertically and it is important that these, and the bottom of the pond, are as smooth as possible to enable the large amounts of waste matter produced by Koi to wash naturally down to the filter intake.  A conventional sheet liner would create too many sediment traps.

The alternatives are to coat the block work with special waterproof cement and resin or to pay for it to be professionally lined with fibre glass.  While these methods are effective, they can be expensive and cement linings can crack and leak as a result of changes in the soil condition. The ideal solution is a tailored-to-fit pond liner, which will fit the Koi pond exactly and create a long-lasting solution.  Box welded pond liners made from butyl or Epalyn carry a 25-year guarantee too.