Designing a Koi Pond That’s Easy to Maintain

Now that you know the basics of sizing and designing a koi pond, there’s still a few factors to consider in your project. Unless your main goal is to spend time cleaning filters and scooping out sludge, you’ll want to design the pond for easy and minimal maintenance. Find out what affects koi pond maintenance and how a proper liner from BTL Liners gets you off to a good start.

A Durable and Fish-Safe Liner

The use of the wrong liner (or no liner at all) does more than just dramatically increase the maintenance required by the koi pond. There’s also a risk of sudden fish death from chemicals leached out of certain liners made from PVC and similar materials. You have to use a fish-safe flexible liner that’s actually tested for its fish safety and not just assumed to be ok. Liners made from reinforced polyethylene (RPE), high density polyethylene (HDPE), and low-density polyethylene (LDPE) tend to work best for these ponds. BTL Liners supplies high quality geomembranes made from all three materials, allowing you to choose the perfect liner for your pond that won’t tear or rip during installation or sludge cleaning tasks.

Koi pond liners also need to last the weathering effects of freeze and thaw cycles and daily UV exposure. You don’t want to move your fish every year or even every few years just to replace the liner and deal with rips or tears. Choose a durable pond liner that can handle a decade or more under the water to reduce the amount of work your pond needs each year.

Accessible Filters and Pumps

It’s natural to want to tuck your filters away out of sight and disguise their sound with cases and covers. However, you’ll need to backwash and change out filter media on a regular basis, especially during the warmer months of the year. Keep your mechanical and biological pumps and filters easy to access so that routine maintenance and occasional repairs are both easy and quick. Your fish can become ill or die within hours if there’s a major pump or filter malfunction. Make sure your water quality maintenance system is always easy to access so you can check it regularly as well.

Properly Located Bottom Drains

Bottom drains are the preferred method for moving water from the pond through a filtration system before it’s returned. A single bottom drain will only work for the smallest of koi ponds. You’ll want at least one bottom drain for each section of the pond with a measurement of 10 square feet. A 20 ft by 18 ft pond would need two drains since it can be divided into two sections that are about 10 ft by 10 ft. If you prefer to measure by volume, use at least one drain for every 6,000 gallons and space them out evenly. Use 4 to 6 in. wide drains, so they accept leaves and other larger debris.

Careful Water Plant Placing

When plants absorb fish waste through their roots, some of the harmful nitrates are eliminated; this naturally reduces algae overgrowth. Koi do best when they have places to hide when they feel the need. Vegetation is a way to not only beautify your pond but help your koi remain stress-free. However, you need to keep plants within reach so you can divide, replace, and repot them as needed. Check the depth required by each plant so you know which edge plants need shallow placement and which floating varieties can go in any location.

Three commonly recommended beginner plants for koi ponds:   

  • Water Hyacynth (Eichornia crassipes) is a hardy floating plant that requires little care. Koi love eating it, but it can still reproduce and spread with ease.
  • Horsetail (Equisetum) is a rush-like plant that grows in water that is only a few inches deep. It does not out-compete other plants. Koi don't usually eat horsetail but enjoy hiding in it.
  • Water Lettuce (Pistia stratiotes) is a floating plant that shelters, shades, and feeds koi. Extensive root systems help reduce algae. It will grow in depths ranging from a few inches to 30 feet, but it needs water temperatures above 66F.

Natural and Artificial Shade

Shade is essential to the koi pond in warmer climates to maintain proper water temperatures and to prevent explosive algae growth that rapidly reduces oxygen levels. However, you’ll need to choose your plants carefully so that leaves and plant debris falling on the surface doesn’t overwhelm your skimmer. In addition to planting living trees and shrubs for natural shade, you can hang shade clothes and sails to reduce the amount of sunlight reaching the surface of the water. These sources of artificial shade are easy to remove in the winter when more light is needed for warmth. Aim to cover at least 50% of the pond’s surface in most locations, with hot climates requiring closer to 70% coverage for water temperature and algae growth control. This should keep algae to a minimum, which can then be further eliminated by the use of a UV light. Without algae, you will have crystal clear water and a good view of your beautiful fish.

Drainage for Water Changes

When following the recommended guidelines of 10% to 20% pond water replacement each week, you’ll will have hundreds of gallons of water at a time that needs discharge. Running all that water over the surface of the soil can flood your landscaping and cause an overload of nutrients from the fish waste. Building a special drainage area with buried drains prevents discharge on the surface. You can also build rain gardens around the pond that are designed to handle nutrient-rich flooding to process the leftover pond water without damaging the landscape.

With these tips, a koi pond should be a joy to maintain rather than a chore. You can also hire a professional pond maintenance service that’s familiar with koi and their needs, which is especially recommended if you’re adding the pond to a place of business.


Liners by BTL

AquaArmor Pond Liner

The most versatile liner on the market today, AquaArmor maximizes protection from harmful UV rays, tear resistance and punctures that cause leaks. Simply the best liner on the market.

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