Building a Fish Pond
Planning Your Pond
It is important to think about the location, size and shape of your fish pond before anything else. The location is important as the pond needs to receive some sunlight but not too much (around 4 to 5 hours a day is best) and it should be in a place that is easy for you to access and that looks good in your garden. If you locate your pond near trees, remember that you will need to spend a lot of time cleaning the leaves out of your pond in autumn.
The number of plants, fish and other creatures that your pond can support depend on the size. The bigger the pond the more life it can support and the easier it is to maintain a balance without too much work. Think about the space available in your garden, and plan your pond around this. The depth of the pond is as important as the size of the surface. Ponds for Koi for example should be no less than 1½ metres deep, and any pond should have enough depth to be at least ½ metre deeper than the water will freeze to so that the pond doesn't freeze to the bottom.
The pond does not have to be the same depth across the whole pond. It is best to have the central area of the pond deepest, surrounded by an area of shallower water and a very shallow marsy area around the edge. This provides plenty of deeper water for the fish, shallower areas for the plants and will allow small animals to climb out by not having steep edges to the pond. The shape of the surface is less important than the shape of the different depths, round ponds are usually easier to build and more natural looking. See the pond example diagrams below for some ideas.
Pond Liners
There are various types of pond liners available, depending on the size, shape and type of pond you want. Flexible liners (usually PVC or butyl rubber) can be used for ponds of virtually any shape, as you dig the pond the shape you want then simply line it with the flexible liner and trim the liner to size. It is best to put a layer of sand under the liner to prevent any sharp stones in the soil below from damaging the liner.
Pre-formed liners are a fixed shape, and require more careful digging so that the liner exactly fits the hole you dig, and is perfectly level. Turn the pond liner upside down and use is to mark out the shape of the hole on the ground. Make the hole a little larger, and line it with a layer of sand before putting in the liner. If the shape of the hole and liner do not match exactly, the lifespan of the liner will be much reduced. You can also build your pond with a concrete liner, however this will require a very large hole to be dug as the concrete will be quite thick and is bedt left to professionals to build this kind of pond. The advantage is that it will usually last for a very long time, and will not require much maintenance.
Finishing Building Your Pond
Once you have dug and lined your pond, you need to finish it. It is best to arrange rocks or paving stones around the edge of the pond, as these will hold the edge of the liner in place and prevent too much dirt from falling into the pond. Paving stones allow easy access to the edge of the pond and can overhang the edge of the pond slightly, covering up any exposed liner. Do not make the overhang too large, or there will be a risk of the paving stone falling into the pond when it is stood on.
You can also edge your pond with grass sloping down into the pond using turf placed over the edge of the liner, however the liner around the edges of the pond must be carefully built to not allow any water to escape but also to allow the grass to survive. See the bottom diagram below for an example.
Pond Example Diagrams
Below are some diagrams with examples of shapes and depths of various sizes of ponds, which you may like to use to base your own pond design on. Click on the images for a larger version.
