Like so many garden projects designing a pond requires careful planning. There are so many options to consider depending on use, size, shape, material and situation. A careful compromise of these factors will produce a pond suitable for your needs that complements your garden. Usage. You need to consider what you intend to use the pond for. The most basic ornamental pond is designed to be a pleasant focal point installed as a standalone garden feature or as part of a wider landscaping project. These are perfect for adding additional water features. If you intend to use your pond for aquatic planting then more specific needs must be addressed. A stepped base or shelf may be needed to accommodate marginal plants of varying heights while baskets can used to enable them to be moved and maintained. The choice and diversity of aquatic plants must be carefully planned in much the same way as designing a garden bed or border, taking into account spread, height, position and colour. If the pond is to be used for fish then its water volume will need to be calculated in order to provide a suitable environment for marine life, dictating the eventual shape and size of your pond. Size. To ensure good water quality a goldfish pond will require a surface area of at least 5 square metres at a depth of 60cm, creating a volume of 3 cubic metres which is 3000 litres. Koi ponds will require a much greater volume of water, in most cases around 5500 litres. There are no limitations on the size of ornamental or aquatic ponds other than the available space and construction methods. If marginal plants are to be grown then a perimeter shelf 30cm wide and 25cm deep should be included. Shape. Determining shape and style is the fun part of designing a garden pond. The type of pond you decide to use will depend on the size, shape and style of your garden. A more formal pond with a geometric shape with is best suited to a patio or decking area, often as a centrepiece. A raised pond is perfect for this configuration, particularly if space is limited. An irregular shaped informal design can be accommodated into ambitious landscaping, blending with the adjacent features or planting. This type of pond is generally sunk into the garden for a more natural effect using marginal plants to merge the design with the landscape. It is often useful to lay out a rope or hose in the garden in the shape of your pond to get an idea how the finished project will look and see how it blends with the existing layout. Construction. Raised ponds can be made from bricks, concrete blocks or stone for a robust permanent fixture. Timber constructions using interlocking boards or railway sleepers provide a lightweight sturdy construction equally capable of containing a large volume of water. Sunken ponds will require some excavation before fitting a suitable liner but the removed earth can be used for a rockery or landscaping. All pond designs will require a liner to create a watertight seal, with a number of options available according to your design. Sunken ponds can use a rigid pre-cast liner which requires you to make the hole to fit the shape. A flexible liner can be used for all types of pond, forming the exact shape of your design. Flexible liners are available in PVC in a range of thicknesses or butyl rubber membrane for more ambitious projects. Pumps and Filters. In order to maintain water quality and avoid stagnation it is necessary to aerate your pond. A pump will circulate the water, prevent it from becoming settled and adds additional oxygen, vital for sustaining fish and plant life in a marine environment. A filter can be added to the pump to remove dirt particles and fish and plant waste. These can be installed as a submersible all-in-one unit or as separate pump and pressure filter devices. Most pressure filters incorporate a “backwash” facility to clean the system safely. Ultra violet light sterilizers can be fitted to reduce algae and waterborne pathogens. Water Features. Pond pumps have the capability to support a wide variety of water feature attachments. Depending on your design these may range from a simple fountain or an ornamental pump housing to a waterfall or cascade built into the landscaping. Elaborate outdoor lighting systems are also available to add an extra level to your design, providing a subtle display of light, colour and shade. A subtle combination of pond style, landscaping and choice of construction materials can be brought together to create your own idea of a water garden, whether it be traditional or contemporary, designed to suit your location and budget.