Starting a New Pond

Installing a pond needn’t be difficult. You can buy solid pre-formed ponds that come in a range of sizes and shapes to suit all budgets. Or you can buy a flexible pond liner that is made of long-lasting plastic or butyl rubber. These liners are sold in large sheets that you cut to desired size – enabling you to have complete control over the pond’s final shape and dimensions. There are many books and a wealth of internet information that offer practical guidance on pond installation. Here are a few things to consider!


The first consideration is location. Choose a level, sunny spot away from overhanging trees and bushes. You may want to position the pond where it can be easily observed and enjoyed. It helps if the pond is located within reach of a garden hose, and you may want it close to an outdoor electric supply if you plan to operate a fountain or filter (in which case, always consult an electrician beforehand).


The next consideration is size. The size of the pond will limit how many fish it can safely accommodate and the number of plants you can have. In general, avoid very small ponds as they can be more challenging to maintain: the bigger the better!



The pond’s depth is also important. Ideally, you want a pond that has a minimum depth of 0.5 metres at its deepest section. This will allow fish and other aquatic life to retreat from winter ice. It’s advantageous to have some shallow areas, for example a shallow ledge or a gently sloping “beach” will allow you to plant marginal plants that like to have their roots wet, and will ensure that terrestrial wildlife, such as hedgehogs, can easily climb into and out of the water.


As for choosing the pond’s shape (its outline), this is largely an aesthetic consideration. You may want to select a shape that fits with the garden’s overall design: for example, a square, circular, or oblong pond may be suitable for a formal garden, whereas a more irregular shape might complement a wildlife garden.


A filter helps keep your aquarium water clean, and that means healthy, happy fish. It works by removing the fish’s solid and liquid wastes that would otherwise accumulate in the aquarium and pollute the water. The most popular type of filter is the electrically driven canister filter – some models are internal (i.e. submersed within the tank), others are external (they are positioned outside the tank – and must never be immersed). Air-driven sponge filters are sometimes used in very small tanks, and these require an electric air pump to operate them.

AQUARIAN® Pond Calculator

We have made the calculation step easy for you. The AQUARIAN Pond Calculator allows you to simply calculate the volume of your pond following some very easy steps. All you need is first to determine whether your pond is a square/rectangle or a circle/oval. Then provide the width, length, and depth in meters into the AQUARIAN Pond Calculator and the calculator does the rest for you.

Calculating the size of the flexible liner

The size of the flexible liner required for the pond (regardless of the shape and size or location of the marginal shelves) is calculated using this simple formula:

  • Length of the liner is the overall length of the pond plus twice the maximum depth, plus 60cm.
  • Width of the liner is the overall width of the pond plus twice the maximum depth, plus 60cm.


  • A pond with overall dimensions of 2m x 4m and a depth of 1m will require a liner of 4.6m x 6.6m

Installing your pond

Once you have located the space for your pond, outline its shape and size with rope or a garden hose. Dig a hole to match the depth and size of the pond. Firm up the base and remove any stones or rocks that may affect the pond base. Add an underlay (e.g. lengths of old carpet can be used) and/or a 2.5 cm layer of soft sand to support and protect the pond base.

If you plan to install a flexible pond liner, drape the liner loosely over the hole, ensuring it is positioned centrally. Hold it in place with bricks or other heavy objects. Add water to the pond. As the pond fills, continually smooth the liner to minimise creases. The liner will conform to the design of the pond as it is weighted down by water. If you are installing a preformed pond you will need to ensure it is level after positioning it in the ground (ponds must be level in all directions). Backfill around the edges, making sure the soil is well packed under the shelves.


Once the pond is installed, you are ready to fill it with water. Tap water is fine for filling the pond, but you must “condition” the water before adding any fish or plants. This is because tap-water contains chlorine-based disinfectants (either chlorine or chloramine) to make it safe for drinking, however these chemicals will harm or even kill pond fish and can harm plants. Anytime you are adding water to your pond now or in the future, even if you are just topping it off for evaporate it is essential to add a water conditioner to make your tap water safe and protect your fish and aquatic life.

Another great addition when starting a new pond or in the spring after cold winter months is the addition of pond salt. Fish need electrolytes such as potassium, sodium, magnesium, chloride, and calcium to maintain the proper chemical balance within their bodies. Select a Pond Salt that provides the essential electrolytes that fish and all living creatures in your pond need to survive.

Once the pond is installed and filled, you may like to add some decorative touches to the pond’s perimeter. For example, you may wish to place decorative stones around the edge of the pond, or perhaps create a “beach” area using pebbles. It’s worth browsing through pictures in pond books and on the internet to find a design that appeals to your personal taste.

Installing a pond Filter

Unless you plan to have a fish-free pond purely for wildlife then you will probably want to install a filter. A pond filter will help keep your pond water crystal clear and free from toxic fish wastes and other pollutants. Most pond filters are driven by an electric water pump which will require an electric supply from the house. The filter will remove dirt and debris from the pond by passing the water through foam pads or similar materials that entrap suspended particles – this is known as “mechanical filtration”. The pond filter will probably also contain special filter media (in the form of pads, foam blocks or other materials) that will become colonised by beneficial bacteria. These beneficial bacteria convert poisonous wastes (in the form of ammonia – produced by fish and other aquatic life) into less toxic nitrite and finally to weakly toxic nitrate. This end-product, nitrate, is used as a food source by aquatic plants. This bacteria-driven process is known as “biological filtration” (and forms part of the “nitrogen cycle” that you may recall from your school biology lessons).

Newly installed ponds and filters will lack the beneficial bacteria that drive biological filtration. It can take several weeks for these bacteria to fully colonise a new pond. In the meantime, your fish and other aquatic creatures will be producing toxic ammonia that can build up to dangerous levels. To safeguard your fish, you can add a commercial “starter culture” of beneficial bacteria to the pond in order to speed up the colonisation process.


Flowing water enhances your pond’s appeal with pleasing sounds and fluid motion. Moreover, fountains and waterfalls add oxygen to the water, which is important to the health of your fish and to the proper functioning of the biological filter in your pond. But whether you choose to run a fountain, or simply to circulate water through your filter, selecting the correct water pump is crucial for successful pond keeping. The size of the water pump you select will depend on what you wish to accomplish. The water pump should be at least large enough to circulate the entire pond volume at least once every two hours.

For example, a 2800 litre pond will need at least a 1400 litre-per-hour pump. Consideration must also be given to the difference in height between the pond’s water level and the highest point to which the water must travel. If you wish to run a stream or waterfall, you will likely need to use a more powerful water pump. Place your pump as far as possible from your waterfall or filter to help ensure that the entire pond is recirculated through the filter.


All garden ponds accumulate a certain amount of waste from dead plants, leaves or grass clippings, algae, uneaten fish food, and fish waste. As waste decays, it creates toxic water conditions and potential breeding grounds for pathogens, removing oxygen and lowering pH levels in the water. Physical removal, such as netting, is the first action to undertake but we cannot remove everything. Adding beneficial, enzyme digesting bacteria is an easy, natural way to keep your pond clean and healthy. Regular addition of beneficial cleaning bacteria uniquely suited to consume pond sludge is recommended. The debris that you cannot net will be consumed through the routine additional of beneficial bacterial, reducing unwanted organic accumulation in your pond.


It’s easy to maintain a healthy and attractive pond provided you undertake a few maintenance tasks every so often. Even if you have a filter installed, the pond will accumulate organic matter and natural acids (arising from the decay of dead aquatic plants as algae, as well as uneaten food, fish wastes, and any leaves that have fallen into the pond) which can reduce the water quality and disrupt the pond’s natural balance. High levels of pollutants will also render the fish more prone to certain diseases. By performing partial water changes you will reduce the build-up of these pollutants. In terms of how much water to change and how often this will depend on many factors including the efficiency of the filter, the size of the pond, stocking density of fish, and the time of year. As a general guide, it may help to change 10 to 20% of the water every 3 to 4 weeks in the summer. Remember whenever adding water to your pond to use a water conditioner to make your tap water safe for fish and other aquatic life.

You should routinely check your filter to make sure that it is running at peak efficiency. Remember to clean or change the media frequently, particularly during the Spring and Summer seasons to maintain a clear pond. When cleaning your filter media, don’t use a garden hose, as tap-water will kill the beneficial bacterial. Use a bucket of your pond water to rinse off the media. Just don’t dump the dirty water back into the pond!


Select the season below for specific maintenance tips.

  • Remove rotting leaves and other large debris with a net.
  • Any vigorous waterlilies may need lifting and dividing.
  • If you plan to buy new fish, or plants, then this is a good time of the year to do so.
  • Your fish should be gaining their appetites, so ensure you are feeding them adequately, following the advice given in the feeding section.
  • The increase in water temperature and daylength may trigger the growth of algae (green water; blanketweed) which will need be kept under control (various methods and commercial pond products are available to tackle algal growths).
  • This is when the pond reaches its peak and the plants will be in full flower. It is a time to sit and appreciate your pond!
  • Hot weather will cause water to evaporate from the pond so you may need to top-up the pond from time to time.
  • The fish will be at their most active, and if they are adult then they may breed and lay eggs. Keep an eye out for tiny dark fry as Summer progresses.
  • Continue to deal with any algal problems.
  • Vigorously growing submerged plants and marginals may require thinning out or trimming.
  • Thin out any submerged plants and cut back those marginal plants whose leaves and stems have turned brown. You want to minimise the amount of decaying plant matter in the pond, in preparation for winter.
  • Also routinely remove any leaves that have entered the pond from nearby deciduous trees.
  • Continue feeding your fish but be aware that their appetites will decline as winter approaches.
  • The fish will become less active and eventually stop feeding as the water temperate falls.
  • In freezing weather, a sheet of ice may completely cover the pond. If this happens, you need to create a “breathing” hole in the ice for potentially harmful gases (produced by decaying organic matter) to escape. Never break the ice using a hammer or other object – this can concuss the fish! Instead, stand a pan of hot water on the ice until it melts through. During prolonged cold snaps you may need to repeat this process each day.


The most popular pond fish are goldfish and koi. When choosing pond goldfish, avoid the fancy “round-bodied” forms (such as fantails and moors) as these may not tolerate winter conditions. Koi are suitable for larger ponds, bearing in mind these ornamental carp can exceed 2 feet in length when fully grown. Other suitable species include golden orfe and golden rudd. Never introduce wild-caught fish into your pond as they are likely to be carrying infectious diseases.


Avoid overstocking your pond with too many fish. Overcrowding can result in health issues for the fish and risks water pollution problems and low oxygen levels. A general rule is to stock up to three to four inches (length) of fish for every square foot of pond surface in a filtered pond (use a lower stocking level for an unfiltered pond). Base this calculation on the estimated adult size of the fish, not their present size. Common goldfish, for example, may reach 25 – 30 cm under optimal pond conditions.

Maintaining your fish in good condition is easy, provided you pay proper attention to their nutritional needs as well as the water quality of their pond environment. Testing your pond water regularly ensures it remains a safe and healthy home for your fish. Testing of levels such as pH, ammonia, and nitrite can help you determine whether you may be overfeeding, and alert you to any potential issues early, when they are more easily treatable. If your water tests show that any of your water parameters are very high or very low, it is important to take steps to correct conditions for fish health and wellbeing. Monitoring the water chemistry of the pond will allow you to catch problems before they develop.

Feeding Your Fish

Although the mature pond will harbour plants and aquatic insects that fish can snack on, your fish will largely depend on you to provide the bulk of their diet. A well-balanced diet will provide the fish with the correct nutrition for healthy growth and development.


The quantity of food required by pond fish will vary according to the water temperature of the pond – the warmer the water, the greater their appetite. Hence, as a general rule, you should feed your fish twice per day in spring and summer. Give them amount of food they will consume in three to five minutes. Remember as autumn approaches and the gets colder their metabolism slows down and they will eat and require less food. So, in very early spring and autumn when water temperature is below 15.5°C (60°F) feed once a day, the amount the fish will consume in three to five minutes. As winter approaches the fish’s appetites will decline further, and as the pond temperature falls to a few degrees above freezing normally about 4.5°C (40°F), the fish will cease feeding altogether.

Nutritional content of fish food is extremely important to fish health, coloration and even water quality within the pond. Choosing a food that is complete and balanced for your pond fish is essential. The AQUARIAN range of goldfish flakes, goldfish pellets, and floating pond sticks are complete and balanced formulas designed for pond fish and they deliver the highest levels of digestibility and palatability while delivering excellent nutrition and colour enhancement. AQUARIAN foods contain the 10 amino acids essential for fish health along with required vitamins and minerals and are therefore perfectly formulated to provide the optimum total dietary protein levels and nutrients. AQUARIAN formulas help to reduce the risk of poor water quality caused by excessive ammonia excreted as a result of too much protein. The amino acid profile of each AQUARIAN fish food is tailored to meet the needs of your pond fish.

Planting your Pond

It is exciting to see the lush foliage and beautiful flowers produced by your aquatic plants. The diversity of plants available can make every pond a unique delight. Aquatic plants will benefit your fish by providing shade and shelter as well as spawning surfaces for egg deposition by goldfish and other fish. Plants help combat unsightly blanketweed and other algae by absorbing nutrients from the water and providing shade, leaving less food and light for algae to grow. Plants also produce oxygen during daylight hours through the process of photosynthesis. However, to assure your pond fish have adequate oxygen a water pump is always recommended. A properly planted pond will allow your water garden to come as close as possible to a balanced environment like those found in nature. As a guide, aim to cover about 50% of the pond’s surface with plants, such as waterlilies and other surface-spreading species.

Plants in the Pond

There are lots of plant species that are suitable for the garden pond, so you may be spoilt for choice! It helps to spilt them into three categories: floating plants; submerged plants; and marginal plants – each discussed below.

The more pond plants you have the better for your water clarity. It is often advisable to place certain plants, such as waterlilies, in special pond plant baskets. This enables you to reposition the plants, prune and separate when necessary, and allows for easy removal during major pond maintenance.

Floating Plants


Floating plants have all or part of their foliage on or near the surface of the water. Some floating plants grow with their roots in the soil and their leaves at the surface, examples being the waterlilies and Aponogeton. Others grow so that the entire plant appears at the water’s surface, with the roots hanging in the water, examples being water soldiers and frogbit (Hydrocharis).


Submerged plants grow entirely beneath the surface of the water. Many are very efficient at utilising nutrients which would otherwise promote algae blooms. Examples of submerged plants include Starwort, Hornwort and Water milfoil. It is recommended to choose British species rather than the exotic submerged plants which can be highly invasive, causing ecological damage to natural aquatic habitats.

Submerged Plants


The third category comprises the marginal plants which grow in shallow water. Most prefer water two to six inches deep – conditions where the roots and crown can be wet, but the stems and leaves are above the water’s surface. There is a huge range of beautiful species to choose from, including various rushes (e.g. Butomus and Acorus species), Marsh marigolds, Cotton-grasses, Ranunculus, and Irises, to name a few.


Click on the below questions to reveal the answers.

Feed your fish AQUARIAN Goldfish & Coldwater Flake Food, AQUARIAN Goldfish Pellets, or AQUARIAN Floating Pond Sticks, 2-3 times a day, only as much as they can eat within 5 to 10 minutes. Do not overfeed fish, as uneaten food will quickly turn to waste and spike ammonia in your pond water. Remember in cooler water your fish will eat less, so in the spring and fall feed your fish once a day or even once every other day the amount of food they will consume within 5 to 10 minutes. The feeding energy of your fish will help you to determine how much and how often to feed your fish.

Adding the right number and size of fish to your pond is important. Adding too many leads to poor water quality and health problems. This is especially true in an unfiltered pond with little or no aeration. A general rule for success is to stock your properly filtered and aerated pond with 3 to 4 inches (7.5cm to 10cm) of fish for every square foot of pond surface area. Remember when you are determining how many fish to keep think about the adult size they will become, not just the size they are today. Goldfish can easily grow to 12” to 15” (30 cm to 38 cm) in length. Koi grow much larger and on average are 24” to 36” (61 cm to 91 cm) in length.

As long as your pond does not freeze to the bottom and an air hole is provided somewhere on the surface of your pond, your fish will survive the winter by resting at the bottom of your pond. You’ll want to invest in a pond aerator or de-icer to maintain an oxygen hole in any ice that forms.

Remove any excess debris that has formed at the bottom of your pond with a plastic rake, net, or other device that will not damage the liner or fish in your pond. As fall approaches and the water temperature drops, your fish will consume less food, so reduce your feeding to no more than once a day or once every few days. Your fish will become mostly inactive when water temperatures drop below 42 degrees Fahrenheit (5.5° Celsius), so you should also stop feeding them around this time. Once the weather turns freezing, your fish cease to digest food as they would when the water is warmer.

If pond fish are fed properly on a regular basis during the spring, summer and fall they can go months during the winter without being fed. Fish can store energy for the long winter months. In cooler water their metabolism slows down, and their energy needs are dramatically reduced. If you keep your pond clean, feed a complete and balanced food such as AQUARIAN products during the warmer season, and do not overstock than your fish are ready for the winter.

The only way to determine if your pond water is safe is to test it. Poor water quality is a stressor for your fish and can lead to sick fish. Good water quality provides the environment for healthy fish. Testing should include pH, ammonia, and nitrite at a minimum. Regular water testing, at least once every two weeks, will alert you if your pond is overstocked, your filter is working properly, or if your pond is being overfed.

Mosquitos need calm water to bred. Having a water pump to circulate the water helps to eliminate this concern. Secondly, fish love to eat mosquito larvae and are a natural food for goldfish. If you have just a few fish in your pond than you will notice that mosquitos are not a concern. In fact, yards with a pond and a few fish have less mosquitos concerns than yards without fish ponds.

Click to learn about Fish Health

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