How to Build a DIY Koi Pond

A koi pond installed in the garden is a great way to improve the general design of your outdoor space and increase the market value of your home. Usually, you’d have to hire a contractor to install a pond but you can actually build one on your own!

The size and depth of the pond will be a matter of preference, but you can research online for various inspiration and designs. Once you have a design in mind, you can start the project and build a koi pond. Below is a basic step-by-step guide on building a koi pond.

Step 1: Checking the Perimeters

Using string and sticks, start laying out the perimeter of the pond and dig a hole. With a shovel and a wheelbarrow, start digging the site for the pond. If the site is very large, you’d have to hire a contractor to excavate the site.

After excavation is done, you want a solid, smooth base to work on. Smooth out the earth, make slopes and keep the base of the pond stable. Remove any sharp debris or rocks. These obstructions could damage the pond liner.

Step 2: Installing the Pond Liner

Start installing the drains and filters in the base of the pond. Make sure the ground tapers so that the drain and cycle will cycle through any fitting you install. Then, cover the base of the pond with a protective layer. You can use old carpets and drapes to avoid leaks on the pond liner.

Measure the pond liner but allow a generous space in case you make errors in measurement. To install the liner, lay it next to the pond while folded. Unfold the pond inside the hole carefully. As you unfold the liner, press the material into the earth for a perfect fit.

Smooth out the liner, especially all over the perimeter of the pond. Resist the temptation to cut the liner too closely because once the pond is filled with water, the liquid will push the liner firmly.

Step 3: Installing the Pond Filters, Drains, and Skimmers

Once the liner is installed into the perfect fit, start cutting holes for the filters, drains and skimmers on the base of the pond. Seal any holes once you’ve fitted the equipment through so the liner remains water-tight. Let the sealer cure for at least 24 hours before filling the pond with water.

When you’re ready to fill the pond with water, use a metered source to get an idea how much volume of water your pond can hold. This is important because you will base the number of fish stock and water levels on the figures.

Step 4: Fill the Pond with Water

Start filling the pond with water. As the pond is filled with water, check for creases and flatten it. Once the pond is full of water and has time to settle in the pond, then you can start trimming the edges of the liner. Conceal the excess liner by burying it with soil.

Step 5: Install the Pumps, Aeration, and Piping

Once the drains and filters are installed, add the pumps, aeration, and piping. At this point, check if the pond fixtures are working and look for leaks. Check for soft spots and make the necessary adjustments.

It will take at least a month for the water to settle. During this time, add water treatments to the water to reduce algae growth and achieve the ideal ambient temperature for plants and koi. After settling the water and it’s ready for the koi, release the fish into the water!