How to Build a Koi Pond

How to Build a Koi Pond

Feb 2nd 2023

Although they originated in Japan, koi ponds have become increasingly popular in the United States. A koi pond can add beauty and serenity to a yard and become the focal point of a landscape. Many folks love to linger beside a koi pond to watch colorful carp glide serenely through clear water.

If you would like such a pond on your property, you could hire a professional to install one. But if you are looking to save some cash, crave the fulfillment of doing a job yourself or are simply a confirmed DIYer, it is possible to build your own koi pond.

Planning a Pond

Several types of koi pond options are available: below ground, above ground and above and below ground. The last two options give you, your family, and guests the ability to sit on a raised fence you build around the pond but require significantly more materials and effort to build. The easiest option is to build a koi pond completely below the ground, so we'll focus on that approach.

Start with some planning. First you will have to decide how big you want your koi pond to be. A popular size is 12 feet by 10 feet, which is big enough to hold about 10 adult fish. Ponds should also be at least 4 feet deep, so they don't freeze solid in the winter if you live in a cold place. Before you dig, check with your local utilities to be sure you won't be hitting any sewer or water lines or electrical conduits.

Digging It

Now you are ready to outline your pond in your yard. Use a rope or spray paint to mark its dimensions. Then dig within the markings with a shovel or an excavator if you have one. When you have finished, remove any rocks and sharp stones from the sides and bottom of the excavation. Install a pond underlayment first to protect the pond liner you will install next.

Pull the pond liner all the way across the excavation and up its sides, holding the liner down with rocks at the edges. Then build a 3-inch ledge of earth outside the liner's edge to help keep dirt, chemicals, lawn clippings and other debris from entering the pond.

Fill the pond with water and check the acid level. You want a pH of between 7 and 8.6. The ideal temperature for koi is around 65º F.

Keeping It Clean

You will also want to install a filter in your koi pond to keep the water clean and clear. Adding a pond skimmer will help remove large debris, which if left in the pond can decompose and cause algae problems.

You should install a pond pump to boost water circulation, which will increase oxygen and promote water clarity. It is also a good idea to install an aeration system to boost dissolved oxygen for the health of your koi. Now you just need to add some fish, sit back and enjoy the serene beauty of your new koi pond.