Under normal circumstances ponds need little in the way of maintenance. Once the aquatic environment has become firmly established maintenance is reduced to a minimum and there is plenty of time to simply enjoy. Naturally a little regular work is needed and it is important to keep a watchful eye on conditions in the pond. However, enjoyment of the pond environment will in itself sharpen the eye of the beholder.

General maintenance It is essential to ensure that there is sufficient water in the pond all year round. Pond water can evaporate very quickly indeed during hot weather. The quality of the water also needs regular checking, i.e. the pH and gH. The acidity (pH) of the water should always be checked after a long period of heavy rain. Any debris that collects in the water should be removed immediately. Any problems involving algae should be dealt with swiftly. Remove any plant residues and keep a close eye on the plants themselves. Plants can come away from their planting baskets or fall over. Water lilies often have a tendency to float to the surface. Return them to their baskets at the bottom of the pond and weigh these down with rocks. Check plants and fish for damage or injury.

Work in spring The pond starts to come back to life. Slowly plants and animals awake from their winter sleep. The first signs of green appear in the water and on the banks. As soon as the temperature permits protective materials should be removed from tender marginal plants. All the old, dead growth can now be cut away. Be careful not to damage any of the new growth, i.e. do not cut back too far. Remove all dead organic material from the water, such as the leaves of last year’s yellow flags. This treatment rejuvenates the entire plant world in and around the pond. Now is the time to divide perennials, planting the young plants in fresh, fertile soil. If you are planting plants in the pond with new soil, make sure this is thoroughly soaked beforehand. Otherwise the baskets will have a tendency to float and the new soil will be washed out. Water lilies that have been taken out of the pond for the winter can be returned to the water and sensitive plants that you put into deep water for the winter can go back to their normal spots. This is also the time to check the pond for any damage that might have occurred during the winter months and clear away any debris that may have collected on the bottom. This should not be done too early in the year. If the water is still very cold there may well be hibernating creatures still dormant in the silt at the bottom. The pump can go back into the pond. The bio-filter can be cleaned and restarted. In early spring oxygenating plants are not sufficiently active despite the fact that the water may contain the necessary nutrients. Algae such as pond scum and blanketweed could take this as an invitation to grow and try to take over the pond. This situation will normally right itself with balance being restored within a short time. However, if it goes on for too long, you will need to act. Blanketweed can be fished out of the water and floating algae or pond scum can be removed via filtration. Once the water temperature has reached 12°C you can slowly start to feed the fish again. Check whether they have come through the winter in good health and show no signs of deformity or injury.

In summer Ensure the pond does not become overgrown. If the ecosystem is to operate efficiently at least two thirds of the water surface must remain open. Filamentous algae such as blanketweed can be a problem in summer but you should try to fight them without taking recourse to chemical agents (available in the shops). These agents will quickly disturb the chemical balance in the water. Simply fish the algae out by wrapping them around a stick and pulling them to one side. Blanketweed can become completely tangled up in oxygenating plants. When this happens it is impossible to avoid pulling up some of these at the same time. The presence of blanketweed actually indicates that the water quality in the pond is very good and that it contains a (temporary) surplus of nutrients. The reasons behind this surplus are often unknown and, of course, there is no way you can know everything than enters the water in your pond from the environment outside it. A high nutrient concentration can be the result of large volumes of pollen being blown into the pond from flowering plants in the vicinity. When the weather is very warm it can do no harm to add extra oxygen to the water by means of a pump that produces bubbles or by activating a fountain or waterfall feature. During this period you will need to take steps to keep down invasive plants, which will otherwise become completely out of hand. Water lilies can be attacked by water lily beetles that will destroy their leaves. As soon as you see any sign of this pest, immediately destroy the affected leaves and beetles. You also need to check fish for disease and injury during the summer.

Autumn As the summer draws to an end leaves will start to fall from the trees. This speeds up as autumn proceeds and many leaves will fall into your pond. Remove as many of these leaves as possible. Covering the surface of the pond with a net is an unattractive measure and it is better to fish the leaves off the surface every couple of days. Leaves generally float for a couple of days before sinking to the bottom. Any leaves that are allowed to sink to the bottom of the pond will be broken down by organisms in the soil as winter progresses and a great many nutrients will be released, which can, in certain circumstances, lead to rot. This should be avoided at all cost. Toxic gases may form and if they are unable to escape, e.g. due to a layer of ice on the water, they will damage fish and other creatures living in the pond. Rotting also uses up huge amounts of oxygen from the water. Dying bog and marginal plants are best left alone. The leaves remaining on these plants provide some protection in winter. However, any parts hanging in the water and likely to rot should be removed. Frost tender marginal plants can be moved to deeper water once they have died off above soil level. This keeps them out of danger of frost damage. The same applies to tender water lilies. Less hardy bog plants can be given additional protection by covering them with branches. However, do not do this unless there is a real threat of frost and remove the protective covering as soon as the temperature permits. During this period oxygenating plants will become less active and this is reflected by the growth of algae, which continue to be active even at lower temperatures. These will seize the opportunity to turn your pond water into a 'green soup'. However, this usually does not last long and normally causes no great problems. Move tender plants indoors and give them a well-lit spot that is guaranteed frost-free. You can stop feeding the fish once the temperature falls below 12°C. They now have to rely on the bodily reserves they have built up in spring and summer. Remove the water pump from the pond, clean and store it until spring. Check and clean the biofilter. Install a small oxygen pump with a 'bubble' stone in the water to generate extra oxygen under the ice in winter. The stone should not be placed too deep, as this would have the opposite effect. Fish should also be checked for disease and damage in autumn.

Winter The pond sleeps. If you have installed an oxygen pump or a bubble stone, you can provide the frozen pond with extra oxygen. An ice inhibitor is very useful for ensuring the good exchange of gases between the water and the atmosphere. If your pond is primarily a fish pond, it may even be advisable to install a water heater. Any hollow plant stems that penetrate the ice layer also help towards a good exchange of gases. This is the reason why a bunch of reeds is sometimes placed in a pond before it freezes over. Everything like this helps. In actual fact, there is not much you can do with the pond during the winter. One thing you must under no circumstances do is: hack the ice to try to create a hole in it. This would generate massive vibrations in the water and could actually kill your fish.

Growth of algae Algae are plants and use exactly the same nutrients as all other water plants. Unfortunately they have the ability to multiply at a very rapid rate when there is plenty of food about. This applies particularly to pond scum, which can turn a pond into a bowl of 'green soup' in a matter of days. If algae spread excessively, light fails to penetrate to the underwater plants below the surface of the pond. If this goes on for too long these plants can actually die off. In early spring algae can produce a growth spurt for a short period because the other plants in the pond are not yet strongly active and have a low nutrient requirement. Algae are just that bit quicker to awaken. If you find that later in the year pond scum shows a dramatic increase, this means that the biological balance of the water is disturbed and action is needed. Your garden centre sells a variety of control substances but you should beware of using chemicals unless you know exactly what you are doing. A more ecologically sound method of combating algae is by using a good biological filter. The appearance of other forms of algae, such as blanketweed, indicates that the water in your pond is in good condition. However, it is better to remove the long trails from the surface of the pond. Insert a stick into the mass and twist it. The blanketweed will wrap itself around the stick and can be pulled out. Algae grow less vigorously in shaded parts of the pond.

Water plants The different planting zones of a pond provide habitats for many different plant varieties. The deep water zone is home to water lilies and underwater plants. At the edges, up to a depth of about 40 cm, you will find marginal plants and the bog or marsh zone contains plants that thrive in waterlogged soil and even shallow water. The highest part of the marsh zone is the wet bank and provides a habitat for plants that like their roots in waterlogged soil but not actually in the water. Further away from the pond we find the garden or dry bank zone. In practice of course these boundaries overlap. Many plants have no problems with fluctuating water depths. It is almost impossible to specify the ideal location fully accurately.

Water lilies and other ground rooting plants with floating leaves Often these plants require quite different water depths depending on the variety in question. For example, some water lilies need water that is at least 1 m deep, while others will be perfectly satisfied with depths of 15 to 20 cm. Water lilies prefer stagnant water and a spot in full sunlight. Never plant them near a spouting fountain. This type of plant needs a good-sized basket in the bottom of the pond and plenty of surface area on which they can spread their foliage. Plant them between mid March and June. Stick to the water depth indicated for the plant. It is very difficult to get lotus plants to flower in a garden pond as conditions are generally too cold. This is the reason why this group of plants is not included in this book.