A primer on koi ponds Location, size, equipment, fish are important choices

Koi swim in a backyard pond.

I grew up in a small town. My first trip to a major city was pre-GPS days. All I had was a map. I saw parts of Chicago’s South Side that were not on the tour. Like most endeavors, it would’ve helped to have someone who knew where they were going.

A few years ago, I took part in the Lowcountry Koi Club tour. If you’ve ever considered a water feature, this is your opportunity to see what’s possible in your backyard and ask questions from enthusiasts that know what they’re doing.

This year, the tour will be May 14. Visit the website lowcountrykoiclub.com for a map and details.

Koi ponds are impressive features that never fail to draw attention. Whether it’s a 50-gallon pond with a few goldfish or a 2,000-gallon pond with waterfalls and fountains, there are fundamental basics that make the design and construction achievable for most homeowners.

A pond will need access to a power outlet for a pump and, possibly, a UV filter. Full sun will allow you to grow water lilies.

Shade will limit planting options but also will be less susceptible to algae. Ideally, you want a water feature where you can easily access it or, at the very least, hear it.

There are two methods to make your pond hold water. A pre-formed container is a semi-rigid tub for small applications.

Despite the thickness, it’s still susceptible to cracking and leaves little room for imagination.

A flexible liner is the second and, in most cases, the preferred method. It is a rubber or plastic sheet. Rubber is more durable. To install a liner, the pond is excavated from the ground. In some cases, a cushioned layer is placed over the soil but not necessarily. Eighteen inches is a minimum depth for koi, but deeper is better. Some koi ponds are four feet deep to reduce stress and predation.

When the sides of the pond are dug steep and deep, it will prevent osprey or blue heron from wading in to steal your babies.

Circulation is essential to keep water oxygenated and clean. Minimally, half of the pond should be pumped every hour. For instance, a 1,000-gallon pond should pump 500 gallons per hour. More circulation is desirable. To estimate pond volume, calculate the cubic feet by multiplying length by width by average depth. Every cubic foot holds 7.5 gallons.

The most appealing ponds are those with clear water. There are numerous ways to keep the water clean. Plants are natural filters.

Aquatic plants absorb excess nutrients that would otherwise feed algae. One method is to fill the waterfall with plants so that all the water circulates through the roots.

Green water is caused by microscopic algae. An ultraviolet (UV) filter is very effective at clearing up this problem. As water is circulated past a UV light bulb, microscopic algae clumps together and settles to the bottom of the pond.

Koi are the most prized of ornamental ponds. They are essentially beautiful carp. They’re also pigs that eat everything. They will keep some aquatic weeds under control, but they’ll also beat up lilies and water lotus so some plants should be protected.

Koi can become quite valuable, but they grow fast so you can start off small and inexpensive.

For many pond owners, feeding koi is enjoyable. Avoid overfeeding at one time since excess food will reduce water clarity. During the winter, when water temperatures are below 50 degrees, feeding is not necessary.

Also consider starting with goldfish, another decorative type of carp. A bagful of 10-cent goldfish will grow rapidly. Shubunkin goldfish are often calico colored with long tailfins. Fantail goldfish can develop very long, graceful fins. When koi are not present, aquatic plants often thrive and provide goldfish cover from predators and lay eggs.

Still not sure if a pond is for you? Mark your calendars for the Lowcountry Koi Club tour on May 14 and see what’s possible. You’ll be digging a hole in your backyard soon after.

Tony Bertauski is a horticulture instructor at Trident Technical College. To give feedback, e-mail him at tony. bertauski@tridenttech.edu.