Q: Why does my water garden turn green and can I prevent it?
Laurie- Bardstown, KY
A: Green water in fish ponds and water features are a common conundrum faced by hobbyists. What causes it, and how can it be fixed?
Green water is the result of an imbalance in your pond’s ecosystem. When too many nutrients – also known as decomposing plant material, fish waste and other debris – build up in your water garden, algae flourish because the nutrients act like fertilizer to those tiny plants. That thriving planktonic algae is what causes your water to resemble pea soup.
To achieve balance in your pond, you need to evaluate and correct the underlying problems that are causing your green water. Here’s a guide that can help you identify the problem and work toward a solution:
- Problem: Too many fish.
Solution: If your water garden is brimming with fish, it may be time to relocate some of them. Overcrowding is a common source for green water because your filtration system may not be large enough to handle the amount of waste being produced. A simple rule of thumb to ensure room for your fish is one fish (5 inches long) for every 10 square feet of surface area.
- Problem: debris buildup.
Solution: After a long winter, waste and debris may have built up in your pond. A good spring cleanout will remove those excess nutrients that are feeding the algae. Here’s an easy step-by-step spring cleaning guide to follow that will help you through the process.
- Problem: Inadequate mechanical filtration.
Solution: Mechanical filtration helps to remove the excess nutrients from the water column. As the water passes through the filtration system, debris is removed and collected in the filter box or skimmer. Check to be sure your filtration system is adequate for your pond’s size and fish population. If it’s not, consider giving it a boost.
- Problem: Lack of beneficial bacteria.
Solution: Beneficial bacteria, like those found in DefensePAC®, are microorganisms that eat through detritus and other algae-feeding nutrients. With little or no nutrients to feed the algae, the green stuff will eventually die off. Learn more about DefensePAC’s components and how to use them here.
- Problem: Inadequate aeration.
Solution: Those beneficial bacteria – as well as your pond’s fish – need life-giving oxygen to thrive, and that’s where aeration comes into play. Air being pumped into the water via a diffuser or air stone will circulate the water column and infuse the water with oxygen. Learn more about the importance of aeration here.
- Problem: Too much sunlight and not enough plants.
Solution: Because algae are plants, sunlight is essential for growth. You can block that sunlight by covering your water’s surface with floating plants. We recommend shading 40 to 60 percent of your pond with water lilies or other floating plants.
Once you’ve cleaned out your pond, checked your filtration and aeration systems, added some beneficial bacteria, adjusted your fish load and added some plants, you should be well on your way to clearing up that pesky algae. A final remedy to try is an ultraviolet clarifier, like The Pond Guy’s® PowerUV™ Clarifier. It’s designed to clear water. As a result, the tiny particles of debris clump together and are removed by your mechanical filtration system.
Good luck keeping that green water at bay!
Pond Talk: What do you do to clear up algae in your koi pond or water garden?
Filed under: Algae Control, Pea-Green Algae, Season-Long Control, UV Filter, Water Gardens & Features, Water Quality Issues Tagged: | algae, green water, pea soup, power uv, too many fish, uv, uv light filtration