Cute little garden froglets

How to Build a Wildlife Pond

There is no better way of attracting wildlife into your garden than by building a wildlife pond. Just about every living creature is attracted to water. It is used for drinking, bathing and breeding as well as providing a home for so many fascinating creatures. 

Pond construction methods vary enormously so getting it right from the start will save you time and money. It will also help you to provide the best possible habitat for wildlife and yourself. This 7 step design process will help you build the perfect wildlife pond.

Step 1 : Decide on the best size for your garden

Whilst it is true that even a ‘washing up bowl’-sized wildlife pond will be attractive to some forms of wildlife it is undoubtedly the case that the bigger garden ponds will attract more wildlife. Ponds are very dynamic habitats that are constantly changing . A larger volume provides more stable conditions.

Step 2 : How deep should a wildlife pond be?

Garden ponds do not need to have a minimum depth to be of value. Water just an inch or two deep is very attractive to most garden birds and many mammals. Reptiles, amphibians and fish also favour shallow areas especially at certain times of the year. It warms up quicker in the Spring and will help stimulate breeding. 

A key requirement for all wildlife ponds is to have extensive shallow areas around the edge. This is welcome news for parents as ponds can present a significant danger to young children and many lives are tragically lost each year. It is perfectly sensible to keep all ponds to a a maximum depth of 50cm. By topping up in times of drought and providing insulation in the depths of winter shallow ponds are highly recommended.

In many situations my personal choice for deeper water provision would be to have a second raised pond. These are much easier to install, as they require little or no digging. They are also safer with small children. Access to the pond by wildlife can still be achieved with the use of ramps and it is easy to provide a small shallow shelf for escaping wildlife or bathing birds.  Management is also easier with effortless drainage and easier access to the raised surface. Draining an in-ground pond in usually a major, but often essential, undertaking.

Step 3 : Choose your pond construction materials wisely

i) Pond Liners

Pond liners are cheap, easy to install and can last a lifetime. They can be retrieved many years later and reinstalled in future projects. The only things you have to watch is they are prone to sharp claws and vandalism. They can be made to fit almost any shape. The ‘secret’ is to deal effectively with the edges. Exposed liner is not only unsightly but also a vulnerable to damage.

ii) Preformed Ponds

For small gardens there is much to recommend a preformed pond. The first big advantage is that they are far less likely to be damaged and subsequently leak. If you have ever tried to locate a leak on a liner pond you will appreciate just how difficult it can be. 

The second advantage is you will not have any creases and folds to contend with. The surface will be smooth, crease-free and easily scrubbed is needed.

iii) Concrete

Easily the least suited to wildlife from almost every angle. It is not a good choice from a carbon footprint point of view. Concrete garden ponds are also difficult to install and are rough on fish skin. The rough surface can be over-coated with fibreglass and is a popular choice for many koi keepers. However it is permanent, inflexible and difficult to repair any leaks. If you have inherited an old concrete tank don’t rush to break it up. Rather think about adding a second or third pond to expand the range of habitats that you can provide.

Step 4 : Water Quality

Water quality plays a vital role in the health of all aquatic life. Consequently managing water quality is an essential feature of any garden pond. Contrary to popular belief, a carefully designed filtration system can greatly improve the health of most pond wildlife. In many natural ponds dissolved oxygen levels can easily reach dangerously low levels during hot summer nights without some form of aeration. 

Anyone contemplating building a wildlife pond should carefully consider incorporating a small pond pump, UV system and a simple filtration system. This is a tried and tested method of maintaining clear, well-oxygenated water in which most aquatic creatures thrive and enable inquisitive children to fully explore and observe the natural pond life. It can make all the difference.

 

Basically we have two choices when it comes to water sources for our ponds. Either we can collect rainwater or we can use what comes out of the tap. .  Bear in mind that water companies are under no obligation to provide tap water that is safe for aquatic life. Indeed most inject chlorine to kill off all life and very effective it is too! 

Fortunately this particular chemical is short lived and will naturally disperse over a 24-hour period. So lesson number one is do not stock a pond with anything for at least 24 hours. If it is necessary to top up pond levels in the summer little and often is a much better plan than sudden larger dosages.

A better plan still would be to pass all tap water through an activated carbon filter. These have the added advantage that they will remove heavy metals, pesticides and many other organic pollutants. As you are only replacing water lost through evaporation you only need a trickle of freshwater thereby reducing the size of filter required.  It is much better to gently add a constant, but tiny, amount of tapwater than to irregularly expose the pond life to large and sudden changes in water quality. Installing an overflow in a raised pond is easy and is of huge benefit and another reason why I recommend this type of pond.

Step 5 : Consider Filtration

 Having established the importance of good water quality it leads us on to discussing the possibility of filtration. The number one problem facing most pond wildlife is the accumulation of nutrients. These so often result in excessive growth of algae that can lead to the following problems;

  • sudden oxygen depletion when the algae die
  • production of toxic chemicals
  • competition for light with a more diverse range of pond plants
  • poor visibility

Pond plants play a vital role in reducing nutrient levels and thereby avoiding the above problems. They are an essential component in all aquaponic systems. The other essential element in aquatic ecosystems are the natural bacteria that go to make up the Nitrogen Cycle. This is a highly complex scientific phenomena but, thankfully, it can largely be left to carry on by itself. A simple filtration system based on plants and bacteria is highly recommended and will avoid many potential disasters.

Step 6 : Select your pond plants carefully

marsh marigold - popular marginal plant for wildlife ponds
Marsh marigolds are a very popular marginal plant heralding the arrival of spring

Plants are an essential requirement for virtually every wildlife pond. They provide natural shelter for many creatures and release life-giving oxygen during the day. They also help to control nutrient levels, especially nitrates and phosphates. Pond plants are becoming more and more popular as a means of improving water quality in aquatic systems.  This is an important choice as once introduced many plants are quite invasive and next to impossible to eradicate if they become a nuisance. Unfortunately the pet trade has offered unsuitable non-native plants that, once introduced are next to impossible to control.

Native plants are nearly always preferable to non-native species on land as well as in aquatic systems. Care in selecting suitable plants at the early stages is usually well rewarded throughout the life of the pond.   Be aware of invasive species that can quickly swap small ponds. Although plants produce oxygen in the presence of light they actually give off carbon dioxide at night. During periods of hot, thundery weather levels of dissolved oxygen can be severely depleted at night.

 

Aquatic plants are often divided into different groups according to where they like to live.  Marginal plants are those that prefer to keep their roots in the wet but their leaves suspended in air. They will thrive in a bog garden and are key to softening the hard pond edges.

Marsh marigold, flowering rush and yellow flag (or iris) are typical examples. Some prefer damp conditions and others are quite capable of thriving in deeper areas.  There is an excellent choice of wildlife friendly plants. 

Oxygenating, or submerged plants, can live completely below the surface. They play a particularly important role in maintaining oxygen levels, reducing nutrient levels  and provide food and shelter for a huge array of wildlife.  

Another important group of plants are the floating types. They may or may not be anchored to the pond bottom but they all have floating leaves that provide useful shelter and shade for many pond inhabitants. Water lilies are a very popular choice and duckweed and frogbit provide similar benefits.

Marginal Plants - a few suggestions

yellow flag - popular and native marginal plant
Yellow flag, or iris, is a native marginal best suited to medium to large ponds
  1. Yellow Flag (or iris) – best suited to the larger pond
  2. Marsh Marigold
  3. Ragged Robin – lovely native species that thrives in damp conditions around the pond edge
  4. Flowering Rush
  5. Water Mint

Oxygenating Plants

1.     Hornwort – excellent choice

2.     Starwort – beautiful fresh green foliage that is present throughout the year.

Floating Plants

water lily - popular floating plant for ponds
Cultivated water lilies are unusually a better choice than native species.
  • Water Lilies – the native yellow species is not usually suitable. It is quite invasive . A domesticated variety is normally the best option and should be selected on the basis of planting depth preference and spread. There are some excellent varieties available so it’s worth doing some research.
  • Water soldier – an interesting native species that does best in rainwater with a lower pH.
  • Duckweed – can easily overrun a pond. Best controlled by fish.

Aquatic Plants to Avoid

1.     New Zealand Pygmy Weed

2.      Elodea crispa

Step 7: Fish

Anyone planning to build a wildlife pond should be wary of the advice so often cited of excluding fish. It is usually claimed that they will eat all the invertebrates. This is clearly untrue and it is now recognised that fish represent an essential group in all pond ecosystems. They and their larvae not only help to control excessive invertebrate populations but, in return, also provide a valuable food source for so many creatures. Newts and dragonfly larvae love to hunt newly hatched fish fry. Indeed, many of our most iconic species rely on a healthy balance of fish and other pond life. Kingfishers, bitterns, herons, otters and ospreys are just a few examples.

We are lucky enough to have quite a selection of small native fish that would make a fascinating addition to any garden ecosystem. Sticklebacks, gudgeon, minnows and stone loach are ideally suited to a small stream that can easily be created in an average sized garden. Provided numbers and size of fish are controlled there is no danger to the overall health of a pond and require minimal management. Herons are super efficient at controlling excess fish numbers and are exciting to watch.

Further Information

The following are excellent sources of sound conservation advice.

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