Common Koi Pond Problems and How to Fix Them

Even the most carefully designed koi pond can develop problems that threaten water quality and fish health. We'll give you practical koi pond maintenance tips that address common issues—from poor water quality and inefficient filtration to fish disease and seasonal challenges.

Water Quality Issues

Although excessive algae growth can reduce oxygen levels and strain your filter system, mild growth is perfectly normal and will not harm your fish. True water quality issues are generally indicated by:

• Fish gasping at the surface
• Fish showing red streaks on the fins or body
• Foul smells

If you notice any of these symptoms, test your water for ammonia, nitrite, nitrate, and pH. Elevated levels may be due to inadequate filtration, overfeeding, overstocking koi, or poor pond maintenance.

Professional koi pond maintenance services can help address these issues while keeping your fish happy and healthy.

Filtration System Problems

Proper filtration is essential for maintaining a healthy pond ecosystem. Here are common filter challenges and solutions:

Clogging

Clogged filters disrupt water flow, which can spike ammonia and nitrite levels. Both ammonia and nitrite can cause skin damage, internal organ damage, suffocation, and acute stress.

The solution? Monitor your filter for buildup, and set a cleaning schedule based on your pond’s needs. While cleaning schedules will vary with pond size and plant choice, we recommend cleaning every 2-4 weeks. Additionally, consider upgrading to koi pond drum filters for increased efficiency and reduced maintenance.

Undersized Systems

Many koi pond owners install filters that are either too small for the water volume or the number of fish in the pond. To avoid water quality issues, we recommend using a filter intended for at least twice the actual pond volume. Koi pond drum filters are particularly effective for large ponds with many fish.

Poor Circulation

Dead zones accumulate debris like fish waste and uneaten food. And as those materials decompose, they eat up oxygen and release harmful compounds like hydrogen sulfide and ammonia. Proper koi pond maintenance means ensuring your pump and returns create a circular flow that eliminates dead spots.

Koi Fish Health Issues

While generally tough, koi can be vulnerable to parasites, seasonal stress, and other issues that you can help mitigate by:

• Monitoring fish for unusual behaviors like rubbing against surfaces and physical changes like developing spots and lesions.
• Quarantining new fish for 3-4 days before introducing them to the pond to prevent disease.
• Addressing health issues promptly. Most problems can be alleviated by improving water quality, using salt treatments, or applying medications when necessary.

Seasonal Challenges

While San Diego’s mild climate makes koi pond maintenance much easier than in other parts of the country, there are still seasonal challenges to be aware of.

Spring Challenges

Abundant sunshine and rain can trigger algae growth, introduce outside pollutants, and alter pH levels. To maintain a healthy environment, install a UV clarifier to control algae. Additionally, test water quality every week and make adjustments as necessary.

Summer Challenges

High summer temperatures can increase evaporation and reduce oxygen. We recommend placing adequate shade over part of your pond, installing an aerator, and topping off water levels when necessary.

Fall Challenges

Falling leaves can clog water filters and reduce water quality. To reduce koi pond maintenance, place protective netting over your pond before leaves fall and keep up with water filter cleaning.

Winter Challenges

Although Southern California winters are mild, December-February cold snaps are not uncommon. Keep in mind that when water dips below 55°Fahrenheit, koi metabolism slows. In such cases, reduce feeding to once every 2-3 days. If temperatures drop below 50°Fahrenheit, stop feeding them altogether until temperatures rise again.

Building Better Koi Ponds: Our Approach

There's a reason people rely on us to bring their outdoor oasis to life—building a koi pond takes experience and expertise. Since 2004, we've been designing and installing custom water features for homeowners, businesses, venues, wineries, and more. With over 20 years of experience, we’ll help you avoid common koi pond challenges with thoughtful design choices that address San Diego’s unique environment. Contact us today!