Managing Ponds in the Landscape

Ponds are a vital part of our landscape. Any water body between 1 m² and 2 hectares in size that holds freshwater for more than 4 months of the year is considered to be a pond. They can be naturally occurring or man-made, and are relatively common features of gardens, parks, golf courses and the wider landscape. The numbers of ponds are in decline, and of those that remain 80% are considered to be in poor condition. However, there are some simple guidelines to assist in pond management and to improve ponds in your care.

Why are ponds valuable?

Ponds are found in a wide range of landscapes, from towns and villages - in people’s gardens or as a feature of a park or amenity area – to farmland, floodplains, heathlands and woods. They are important features of our landscape and we should strive to retain as many as possible as well as creating new ones where space allows. If a pond is well maintained it will provide an aesthetically pleasing feature for people to visit and enjoy. They are often a focus for town or village life, providing a place of tranquillity for people to simply sit and enjoy – something that can be difficult to find in today’s fast-paced, highly connected society.

Perhaps more importantly though, ponds attract and support wildlife and the presence of a pond in an area will significantly increase the biodiversity of the space. It is estimated that at least two-thirds of our freshwater species are supported by ponds. This includes a wide range of insects, amphibians (frogs, toads & newts) and fish right through to larger mammals, birds and plants. Some will be threatened species which require this unique habitat to breed or survive.

How should I manage my pond?

It is difficult to provide specific management advice for ponds as the requirements will vary depending on size, depth, landscape, vegetation and wildlife. However, management work should always be preceded by simple planning: consider the function of the pond – what do you want it to do? What are its existing assets? Carry out a risk assessment to aid your decision making and ensure that you are aware of any legal requirements. In particular, make sure that you obtain the relevant statutory consents, if applicable, to avoid any harm being caused to vulnerable species during work.

There is no ideal time to carry out management work on a pond as different species will be affected at different times of the year. Consider the following as good practice:

Water work is easiest when water levels are low in late summer/early autumn. At this time most animals have reproduced and moved on or died off and plants have started to die back after dropping their seed.
Late summer/early autumn is the best chance to carry out any clearance work but take care to avoid removing too much silt as it could contain eggs and the grubs (larvae) of insects.
Remove fallen leaves from a pond regularly, particularly around autumn. Leaves that remain in the pond will increase the nutrient content, encouraging algal growth, especially once conditions warm up in spring.
If necessary cut back surrounding trees to minimise leaf contamination. Tree work is best completed in winter (Nov-Feb), to avoid disturbing nesting birds.

Common problems with ponds

The main problem encountered with ponds is the growth of algae. Apart from looking unsightly, the presence of algae will reduce the oxygen levels in the water which can be catastrophic for other pond life, both plant and animal. The presence of algae can also create a physical obstacle to activities such as irrigation, water sports and ﬁshing.

There are hundreds of different varieties of algae, some that are suspended in the water, others that spread across the surface in long fibres. The main symptoms you will see if algae are affecting a pond are:

Floating green scums
A ‘pea soup’ effect caused by the fine algae suspended in the water
Blanket weed or silkweed; very common pond algae which have dense growths of hair-like green strands that float under or on the surface or cling to plants at the side of the pond.

Most ponds will encounter an algal problem at one time or another but it tends to thrive where they are located in sunny positions, with very little planting to provide shade across the surface. Situations where the nutrients phosphate and nitrate are present in the pond water will also encourage the problem. This might be as a consequence of too much sludge (organic matter) on the bottom of the pond; falling vegetation (tree leaves); fish faeces; or the leaching of nutrients into the pond via surface water run-off from surrounding ground (especially where fertiliser has been misapplied) or through connecting drainage channels.

How can I eliminate pond algae?

The physical removal of pond algae is possible but only in small ponds. It can be disruptive to wildlife and will not eliminate the problem altogether. An alternative is to use a pond treatment product such as ProCrystal from ICL. ProCrystal is designed to control swimming or ﬂoating unicellular and ﬁlamentous algae found in ponds or enclosed expanses of water.

ProCrystal contains a blend of bacteria that quickly consumes and degrades the excess nitrogen (nitrates and ammoniacal nitrogen) and phosphates in pond water that algae feed on. The algae die swiftly after treatment by being deprived of the nutrients essential to their development. As a result the natural balance of the environment is restored and the clarity of the water is improved in days.

When should I use ProCrystal and how should it be applied?

It is best to apply ProCrystal as soon as algae start to develop or when conditions are suitable for their spread, generally from spring to the end of summer and even early autumn. ProCrystal is supplied in sachets that should be dropped/thrown uniformly on the surface of the water. It can be applied from the water’s edge or, for large ponds, from a boat. Once applied, ProCrystal’s unique and harmless bacteria will rapidly spread throughout the volume of water. Repeat applications should be made to maintain water clarity throughout the desired period.

To achieve the best results…

The presence of a nutrient source entering the pond will prevent the levels of nitrate and phosphate from being reduced. So, make sure that you take steps to minimise surface water run-off from surrounding ground, leaving a buffer zone of longer grass or vegetation around the pond and down embankments. Also, check for the presence of inlet drains into the pond that might be carrying nutrients within the discharge water. The results achieved using the ProCrystal product are unlikely to be optimal where such drains are present.

Follow the instructions for applying ProCrystal correctly; in particular, pay close attention of the application rate advised on the product label. The application rate varies significantly depending on the depth of the pond being treated and you must be confident that you have an accurate measure of the area of the pond you are treating. For a pond less than 1m deep, ProCrystal should initially be applied at 300 g per 100 m² of pond (remember that sounds a lot but in reality it is only 10 m x 10 m) with repeat applications made every 30-60 days at 120 g. For deeper ponds (> 1 m²), the initial application should be at 500 g per 100 m²of surface area, repeated at a dose of 200 g every 30-60 days subsequently.

In summary, ponds are integral to our landscape and provide are a valuable asset that we should strive to maintain for the benefit of the community and environment alike. Good maintenance will go a long way to keeping a pond in good condition but they should be monitored continuously to identify problems as early as possible. Algal problems can be catastrophic to the presentation, usage and wildlife of a pond and should be tackled at the earliest opportunity. ProCrystal provides an environmentally friendly treatment that can be easily administered to tackle the problem quickly and efficiently. If you have a pond in an area under your care, make sure it’s at the top of your shopping list should you encounter problems.