Koi pond construction | Construction advice and koi carp proof planting tips

A koi pond is the perfect way to enjoy the stunning beauty of koi fish. Originally from Japan, where they have been bred for centuries, koi carp have been bred in countless colors and patterns over the years, making them truly stand out in the pond world. But how do you actually begin to build a koi pond? And what are the costs and maintenance you need to think about?

All about koi ponds

• What is a koi pond?
• What aquatic plants can go in a koi pond?
• Supplies for in a koi pond
• Costs for building a koi pond
• Koi pond dimensions
• Preformed pond basin or pond liner?
• Protecting koi carp from herons
• Koi pond maintenance in the winter

What is a koi pond?

A koi pond is a specially designed pond for keeping koi carp, these ornamental fish native to Japan are highly valued for their colorful patterns and soothing swimming behavior. A koi pond usually has a depth of at least 1.5 meters and is designed to provide a suitable habitat for koi. A good koi pond should be able to maintain water quality through filtration, aeration and water circulation. The water in the pond should be free of toxins such as ammonia and nitrite, and the pH level should be within an appropriate range to maintain koi health. A koi pond can vary in size depending on the quantity and size of the koi fish kept in it. Some koi ponds are constructed in a natural setting, while others have more stylized designs with waterfalls, streams and decorative elements to create a soothing and visually appealing environment. Unlike other ponds, a koi pond is all about the pond fish. Thus, a koi pond is a pond specifically for your koi carp. Many keepers of such a pond opt for a pump and filter system to keep the pond clean because the fish love nibbling on aquatic plants. Nevertheless, it is possible to set up your koi pond in a completely natural way, for example by choosing the right and sufficient and different types of aquatic plants or by installing a plant filter in the pond.

What aquatic plants can go in a koi pond?

Owners of a koi pond often think that it is not possible to add pond plants to the pond because the koi will eat them. But this does not have to be true, it is just important to be well informed and choose the right kind of aquatic plants. Pond plants that can be added to a koi pond are plants that grow quickly and are somewhat harder and firmer in structure. For example, rather than waterweed, choose the oxygen plant: hornwort. Hornleaf can grow up to 10 centimeters a day, if you add the recommended amount of hornleaf to your pond, the koi's will not be able to resist eating it and will accept it. Crabberry is also a nice addition to the koi pond, as the hard structure and prickly leaves of the aquatic plants are not attractive for the koi to nibble on. The most important thing is that the carp have space in the pond, when they have this, they are more likely to leave aquatic plants alone.

Supplies for in a koi pond

Before building a koi pond, it is important to be aware of your options. If you want to create a natural pond for your koi, that is, without a pond pump and pond filter, choose suitable and sufficient pond plants. It is also important to add a layer of 8 to 10 inches of pond substrate to the pond so that the plants can root well in the pond bottom. It is also important to add beneficial pond bacteria to the water, these bacteria nestle between the porous rock of the substrate and will keep the pond, along with the plants and pond substrate in balance.

Costs for building a koi pond

The cost of building a koi pond can vary greatly, depending on the size and materials used. For a 10 m3 koi pond without a poured concrete tub, but with EPDM liner, bottom drain and a 3 m3 plant filter, the cost can be between €5500 and €7500. Note that the cost does not include the price of the koi carp themselves. Read up well in advance about building a pond and about setting up a pond.

Koi pond dimensions

To give your koi fish enough living space in the pond, a minimum depth of -1.5 m is recommended. Koi fish grow to about 80 cm on average, so with this depth they have enough room to move around. In addition, this depth helps keep the water temperature stable during cold winter months. As a rule of thumb, you can keep about 1000 liters (1 m3) of water per koi carp to determine how many koi you can have in your pond.

Preformed pond basin or pond liner?

Creating your own pond by digging a hole and lining it with pond liner has a number of advantages over using a pre-formed pond container. First, shaping the pond yourself offers more freedom in designing the shape and size of the pond, allowing you to better create a pond that fits your specific needs and desires. In addition, pond liner offers flexibility and durability because it is able to move with the ground and any movements in the ground, whereas pre-shaped pond liners are less able to withstand this and are more likely to crack or tear. In addition, pond liner is often more economical than pre-formed pond liners because you only pay for the amount of liner you actually need, while pre-formed pond liners are often more expensive because of the additional costs of manufacturing and transportation. So all in all, forming your own pond and lining it with pond liner can be a more flexible, durable and cost-effective option than using preformed pond liners.

Protecting koi carp from herons

For any koi pond owner, the heron is a natural enemy of the fish, which can cause anxiety. Although people sometimes devise complicated defense systems, a simple PVC pipe at the bottom of the pond can often provide enough protection. The fish recognize the danger and quickly swim into the tube to be safe. In addition, a floating plant island that includes crabweed and a water lily can provide a suitable hiding place for your koi. If the plant island is sufficiently present, the fish will quickly feel at home here.

Koi pond maintenance in the winter

With a koi pond, it is imperative that it not freeze over during the winter. This is bad for oxygen levels in the pond. One option is to cover the pond with a winter cover, but you can also use a ball. If you let this float and move on the surface of the water, it will prevent the water from freezing over. Also, make sure that the koi carp get enough fish food before winter sets in. During the winter months, fish have a lower metabolism and need less food. Overfeeding can lead to water pollution and health problems in the fish.