Tools and Materials
Product costs, availability and item numbers may vary online or by market.
What Should I know About a Koi Pond?
Koi fish, also known as Carp, are a hardy and easy to care for addition to a backyard pond. If done properly, they can live for 20 years or more. Because Koi will keep growing throughout their life, they need adequate room to live. A good beginning Koi pond size is about 1,000 gallons, which requires a space of about 6 feet by 8 feet with a depth of 3 feet. Koi need the extra depth to be able to manage extremely cold temperatures and ice that may form on the top of your pond. This depth also provides cooler water in the summer. Our guide will give you directions on how to build a pond that can highlight your backyard and the colorful fish that will playfully swim there.
Choosing a Location for Your Pond
In looking for a space for your pond, consider the following:
- The pond should be on level, well-drained ground.
- Try to keep the site close to an outdoor ground fault circuit interrupter (GFCI) outlet and plan the most direct line possible between the house and the pond for the pump power cord.
- Make sure the site isn't directly over underground pipes, cables, sewer lines, septic fields, etc.
- Ensure there's a nearby outdoor faucet so you can add water to the pond from a garden hose as needed.
- Consider sun and shade. Adding fish to the pond means you will need to balance the sun with some shade during the hottest part of the day by adding water lilies or lotus pads. Small ponds benefit from partial shade since high water temperatures promote excessive algae growth and increase water evaporation and are not beneficial to the fish.
- Avoid large trees and areas subject to strong winds. Leaves and needles can contaminate the water and accumulate on the bottom of the pond, blocking the pump and filtration system.
Before beginning any excavation, call 811 to check for underground utilities.
Make sure your plans comply with homeowners association guidelines and local building codes.
Create Your Koi Pond with a Flexible Liner
Because Koi need a deeper pond than a preformed unit can provide, it may be best to use a flexible pond liner for your backyard space. The flexible liner will allow you to customize the shape of your pond to fit your intended area.
It’s suggested that you buy a liner that’s one to 2 feet larger than the planned layout of your pond. Check the manufacturer’s recommendations for specifics. For this example, our pond is going to be 6 feet wide by 8 feet long and 3 feet deep. The suggested liner size for this pond will be 21 feet by 23 feet.
Plan to install the liner on a warm, sunny day. Spread it out on warm pavement for 15 to 20 minutes to make it easier to handle.
Instructions
Installing Your Pump and Filtration System
How Do I Maintain My Koi Pond?
Proper care of your pond and Koi fish is an uncomplicated process but one that needs to be followed with regularity for the health of both fish and pond.
- Keep your filtration system clean. Make sure it can handle your pond’s capacity and clean it regularly to avoid clogging from debris.
-
Make sure the water has the proper bacteria levels. Beneficial bacteria is necessary, especially when adding water from your household water system.
- Feed your fish and watch as they eat. Koi and other pond fish can get a lot of food from plants, bugs and algae, but additional feeding with a high-quality fish food can deliver nutrients and protein to keep them healthy.
- Keep your fish population balanced. Due to the amount of water Koi require, you do not want to overcrowd, especially with a smaller pond.
- Watch your pond water in extreme weather. Although hardy, water that is too cold or too warm will harm your Koi.
Here Are Some Frequently Asked Questions About Koi Ponds
How deep should a Koi pond be?
A koi pond is best with a two to three foot depth. Koi ponds need more depth than garden ponds to be able to handle weather extremes. Koi fish do best in water temperatures from 59-77 degrees Fahrenheit. In winter and summer, the deeper water can provide proper temperatures for them to survive.
How much does a Koi pond cost?
Koi pond cost is relative to the size and layout of the design. A small basic DIY 6-foot by 8-foot pond can be done for less than $2000, but larger and more elaborate Koi pond ideas can cost ten times that.
Do Koi ponds need a waterfall?
While not essential, adding a waterfall to your backyard Koi pond can be beneficial to your fish in a couple of ways. First is the addition of oxygen to the water. This extra oxygen is good for the growth of beneficial bacteria, which in turn is good for your fish. Second, a waterfall will help keep water circulating to help prevent the growth of algae, reducing the need for the addition of chemical algaecide. For information on adding a waterfall to a pond check out our article How to Build a Pond or Water Garden in Your Yard.