Let pond life brighten up your garden

It's not quite a sweet babbling brook, but a garden pond can be a haven of tranquillity. Build it yourself or call in the professionals, writes Richard Phillips

With the Chelsea Flower Show in full swing, and summer almost here, many of us are thinking about ways to improve our gardens.

One of the cheapest, and most visually pleasing, is a small garden pond. As well as a little haven of tranquillity in your garden, it should prove a low maintenance feature after the initial hard work is done.

Nick Cromby, a television producer who lives in west London, says the motive for his ponds - he has two - came from his love of water. A sailor and former fisherman, he would have liked a garden with a river running through it. Failing that, he settled for the ponds, and built them both himself.

Garden ponds come in many shapes and sizes. Even a pocket-sized garden can accommodate something pretty and meaningful, without it taking up too much space.

The smaller the space available, the more likely it is you will have to opt for the simplest design - an oval or circle. But the greater the space, the more imaginative you can be. Kidney-shaped or stepped pools are among the possibilities to explore.

You can also have a raised pond, as Nick Cromby does, with walled sides. This is chiefly to prevent toddlers falling in, but a brick platform around the rim also serves as seating, for dangling your feet in the water on a hot summer day.

The angles of the sides can also be varied, with one side sloping gently down to the base and the other steeper. Or you can have some sort of stepped terracing on one side, through the way the brickwork is laid. This presents a natural arena for viewing your fish, and a spot from which to feed them. It would also be an ideal frog-spawning area.

Building a small pond is fairly straightforward. However, if you are looking to build one of substantial size - say, two square metres or more in surface area - it may be worth consulting a landscape gardener. The Association of British Landscape Industries can give you details of their members with expertise in pond design near you.*

Professionals are better placed to offer advice, and to say how and if your ideas can be implemented. They will also know the factors to consider in locating your pond in the garden. Trees can be a big problem because of autumn leaves, especially for the fish. One solution can be to stretch some fine nylon meshing over the pond when the autumn leaf fall is at its heaviest.

All ponds need a waterproof lining. Landscape gardeners recommend two layers: the first, in terylene, lies next to the brickwork, and protects the second, waterproof lining from any sharp edges. For this second layer, professionals recommend a rubberised layer of butyl, which comes with a 25-year guarantee, for the waterproof layer. PVC is a cheaper alternative, costing around pounds 50 for a single sheet for a small pond. All the materials for your pond can be bought from specialist suppliers, found in the Yellow Pages under "Aquarium and Ponds".

Once the pond bug has bitten, there is almost no limit to the money to be spent on improvements. Adrian White, managing director of AJW Construction, a Nuneaton-based landscape design business which specialises in water works, says the most important point is to plan ahead. "Many people are so delighted by their first pond, that they want to do more later on. But they find they can't, because they didn't make allowance for any expansion."

The basic construction for a pond should be a minimum of a concrete basin with a double brick lining built into it. Water is heavy, Mr White emphasises; only a well-built pond can take the weight without cracking, or rupturing the lining. For a surface area of one to one-and-a-half square metres, he recommends a nine-inch brick lining, which will require the width of two layers of bricks.

As a rule of thumb, a pond which is one metre across, should be at least three feet deep at its base. This allows the fish enough depth of water in winter, when they are least active and need to conserve energy, and helps prevent a pond from freezing entirely.

You should allow for drainage of any overflow from the pond. Heavy rain can easily flood a small garden pond, and it is best if some sort of run- off channel is provided towards the side of the pond where it will disperse the quickest.

When you have built your pond, next comes the fun bit - stocking it with fish, plants or both. Unless you belong to the minimalist tendency, ponds look better stocked with plants. An aquatic environment, where fish and plants live in balance, can be achieved naturally: the plants aerate the water, which prevents the formation of alg which can kill off the fish by depleting the oxygen levels in the water. Common plants include water lilies, bulrushes and water mint.

However, you should consider whether you want to use pumps and cleaning filters to maintain optimum water condition. Broadly speaking, there are two sorts of filters available. The first, and most common, sort is a biological filter. A pump can usually be obtained for pounds 100 or less, with a simple biological filter costing around pounds 25. One of these will circulate and clean 400 gallons of water an hour, and aerate the water as well. A second and more sophisticated type of filter can be installed, which uses ultra violet light to destroy bacteria.

Before building a pond, you should consider whether you would like the convenience of a pump, which should keep the water crystal clear. If you go for a pump, check out prices and specifications before digging up your garden, as the choice of pump may well make a difference to how the pond is built. The simplest pumps are submersible, and need no installation expertise.

This sort of equipment can add rapidly to the expense of the project. A small, one-metre square pond, with no additional equipment, will cost from around pounds 750 to build if you buy in the labour. But extras can easily bring the total to pounds 2,000 including labour. You can save money by doing it yourself wherever possible, but some of the more expensive equipment is fairly sophisticated and it may be better to have professionals install it.

However, as Nick Cromby says, his ponds stay perfectly clean, all through a thriving combination of plants and fish.

Finally, it may be worth examining the insurance aspects of digging a pond. Buildings insurance only provides limited cover for a garden pond and its accessories, usually of up to pounds 300. There are, however, a few stand-alone garden policies available. The Association of British Insurers (0171-600 3333) should be able to point you in the right direction.

British Association of Landscape Industries, tel: 01535 606139