Pond Design
Pond design is an important factor that should be considered before building any pond. It will have an impact on the actual workings of the pond, the work required to maintain the pond and even the health of the pond life. Achieving a balanced ecosystem is the key to healthy pond design.
Some of the pond design aspects to consider are:-
Pond shape
Pond shape depends on your personal taste. However, it is important to have the correct pond depth for a healthy pond environment.
Pond size
Pond size is determined by the area that you have available. This may be a small bowl or tub for a courtyard or balcony to a large in ground pond with a waterfall.
Pond profile
The pond profile or cross section does have an influence on the growth of plants, control of algae and the water temperature. A shallow saucer shaped pond has a large surface area to volume ratio. This allows more sunlight to shine on the surface and heat the water. However, at night this heat is also lost faster. This creates an environment which has greater changes in water temperature which is not so pleasant for fish or other aquatic life. It also stimulates greater algal growth. A pond design with the same surface area but steeper sides, holds more water and therefore has a lower surface area to volume ratio. The larger volume takes longer to heat up in the sunlight and is slower to drop in water temperature at night. This creates a more stable environment which is much better for plants and other aquatic life.
In ground or above ground
A pond design that is set into the ground is preferable as the ground around the pond helps to stabilise the water temperature. That is not to say that you cannot have a smaller bowl or tub as a water feature. But it must be realised that this type of water feature may require a little more care or maintenance.
Pond plant depths
Pond plants have different needs in relation to water depth. Oz Watergardens have developed a system for classifying plants according to their optimum water levels. To simplify plant selection we have divided the pond into FIVE Pond Plant Zones. This can be a useful guide to plant selection and basic pond design.
Ideally ponds should be at least 45cm deep but can be more than a metre.
Submerged aquatic plants such as Waterlilies are self adjusting to water depth. Most plants supplied to Nursery Garden Centres have been grown in shallow water in order to make them easier to transport. However, if your pond is deeper and all the leaves are below the water surface, you have two options available. Firstly, you can leave as is. The plant will produce new leaves which will grow up to the water surface, while the older ones die off (resulting in no harm being done to the plant). Secondly you can place bricks / pavers (being careful not to damage your pond liner) under the pot to raise the plant.
Waterfalls and fountains
Waterfalls and fountains can add charm to a water feature and the sound of splashing water can be a soothing distraction to our often hectic lives. Moving or splashing water also improves the health of the pond by increasing aeration and therefore improving the oxygen levels. Most plants with floating leaves do not like water splashing continuously on them as the leaves suffocate, yellow and can die. We recommend placing these plants in areas clear of splashing.
Filtration
Filtration, in a good pond design, should not be necessary, provided that there is the right balance of sunlight, water depth, water volume and plants. However, the extremes of temperature, light levels, high fish populations and/or low plant numbers can affect the water balance. Thereby creating an environment where algae can flourish and cloud the water. In instances such as these there may be simple remedies such as introducing more plants. However, if high fish numbers are to be maintained, then biological filtration should be installed.
Filtration needs and types can vary greatly. Mechanical filters trap particles. Skimmers can help save a lot of work in pond maintenance, as a well designed and maintained skimmer system, can potentially collect more than 75% of the debris before it sinks to the bottom of the pond.
Biological filters provide a medium for beneficial bacteria to grow. The bacteria feed on the toxic ammonia produced from fish waste and decomposed plant matter. As a byproduct, the bacteria produce nitrates and nitrites which are then a food source for the plants.Ultraviolet filters are designed to sterilise the water passing through them and may be appropriate for some pond systems. They are often used in conjunction with other filtration methods, as the water passing through, must be relatively clear of particles for the light to effectively shine through.
Construction materials
A pond built from concrete, limestone, or marble will also tend to have a high pH, which can contribute to greater algae growth. Ponds constructed from these materials can be treated with sealants to prevent the lime leaching out and affecting the pH levels.
Plastic liners, though cheap, should be avoided. The cost and effort of repairing damage and leaks tends to outweigh the initial investment.
Preformed fibreglass or plastic pond are an easy solution to pond construction, however they do limit the potential size and shape and are often difficult to add to or extend.
EPDM and Butyl rubber liners are recommended for most ponds as they offer flexibility in the pond design. They are durable and allow for easier and more natural pond designs. These materials can also be joined to create much larger ponds.
Capturing the rainwater
Why only have water storage tanks to capture and store the rainfall? When you can develop a pond design that naturally captures run off of roof tops and channels the water into your own billabong. Care should be taken not to divert all the garden run off into the pond. This water often contains a lot of organic matter and increases the nutrient levels in the pond water, resulting in increased algal problems.
We live in the driest continent in the world and yet we landscape in a way that results in the little rainfall that we do have, to run off down the drains and out to sea. This precious resource should be harvested and retained on site for the benefit of the local environment. Once our urban billabong is filled, excess runoff would then be able to continue to support other areas of the garden. Replenishing natural ground water has also been overlooked in many garden designs.
Before you start...
- Ask yourself why you want the pond?
- What is your dream pond?
- What do you like to do outside?
- What kind of lifestyle do you live and what would you like it to be?
“The answers to these questions will help you decide the style of pond. This is a great place to begin.”