How to Build a Round Koi Pond

Koi are colorful, easy-to-care-for fish.

Though koi are resilient fish that survive well in a wide range of environmental conditions, it is important to construct a pond that facilitates healthy water quality and provides enough space for the fish to develop. While building a round koi pond yourself may seem like a daunting task, with careful planning and construction, adding a water feature to your landscape that is easy to manage and keeps fish healthy is a simple process. And in the end, you will have an attractive centerpiece for your home garden.

Things You'll Need

• Garden hose
• Shovel
• Sand
• Pond liner
• Pond filter
• Rocks
• Driftwood
• Native plants

Instructions

1. Lay out a garden hose in the shape that you want to construct the round koi pond. Koi ponds should have a minimum diameter of 6 to 8 feet. A garden hose is flexible and easy to adjust in order to get an accurate estimate of how the pond will appear in your landscape.

2. Mark the area around the garden hose with spray paint once you decide on the final shape of the pond.

3. Excavate the earth inside the painted line using a shovel; the depression should be at least 4 feet deep so that the koi can survive winter temperatures in the pond. Remove any rocks and set them aside for use later.

4. Place a 2- to 3-inch layer of sand in the bottom of the depression to create a soft substrate to protect the pond liner from punctures caused by rocks or other debris that may fall into the pond.

5. Unfold the pond liner in the hole. Using the garden hose, fill the bottom third with water to hold the liner in place.

6. Pull the pond liner edges taut around the rim of the pond and place rocks over the liner to hold it in place.

7. Install the pond filter and plug it into a GFCI outlet to test the plumbing. While several types of pond filters are readily available from home and garden stores, a standalone submersible pond filter is one of the easiest to install in a koi pond. Simply place the filter in the pond and gently position it so that it remains level on the bottom of the pond and completely under the water surface before turning the pump on.

8. Decorate the edge of the pond to create a natural appearance. Use river rocks and short pieces of driftwood to fit the round shape of the koi pond.

9. Add native plants in small openings between rocks and driftwood along the edge of the pond to fill space and create depth along the border. Native plants also provide shade, which helps keep water temperatures cool in summer and attracts insects and small vertebrates, both of which are natural foods for koi.

10. Fill the rest of the pond, plug in the pond filter and allow to stand for 48 hours. Observe the water level carefully to ensure that there are no leaks or problems with the pond filter before adding koi to the pond.

11. Add koi to the pond. Start with only a few koi the first season to ensure that your pond is functioning properly before adding more the following season.

Tips & Warnings

• Dig a small shelf into the side of the depression when excavating the pond site to create a natural ledge for growing aquatic plants.

References

• University of Illinois: Koi and Goldfish Pond Winter Care
• Langston University: Pond Design
• University of Kentucky: Species Profile -- Koi and Goldfish