Explaining the Nitrogen Cycle

A well-balanced and healthy ecosystem in a pond is the environment needed for aquatic plants and fish to thrive. Building and maintaining this pond ecosystem is easy once you understand the basics. In this article, we will explain the nitrogen cycle and why it is vital to aquatic life in a pond.

Nitrogen Cycle Overview

The nitrogen cycle in a Koi pond is the biological filtration system that regulates safe levels to be able to support aquatic life like fish and plants. Without an established ecosystem, levels of nitrites and ammonia will increase, putting your fish in danger.

Once a pond is built, nitrogen from the air enters water through rainfall, runoff and wind. Branches, leaves and other debris can also contaminate the pond. Waste from fish and leftover fish food in Koi fish ponds will also contribute to the debris, and overtime the debris will begin to decay with the assistance of beneficial bacteria or microorganisms known as Nitrosomonas and Nitrobacter. While the debris breaks down, ammonia is released into the water. Nitrosomonas consume oxygen and ammonia in the water and then produce nitrites. Nitrites are harmful to Koi, so another organism known as Nitrobacter will decrease the nitrites in the pond and turn them into nonharmful nitrates. Then the nitrates are reduced by changes in the water or they are consumed by aquatic plants and algae.

New Ponds Have New Bactria

Establishing a healthy population of good bacteria, Nitrosomonas and Nitrobacter is not an instant process. So if you just built a pond, you should wait four to six weeks before you add fish, otherwise the ammonia and nitrite levels may be too high. Try adding beneficial bacteria to your pond and boosting dissolved oxygen levels with an aeration system.

Maintaining Bacteria Levels

At the beginning of spring when ponds are waking up after a cold winter, a similar cycling process happens. Some Nitrosomonas and Nitrobacter will survive in the gravel and filtration media and begin to increase but giving them a hand is a good idea. Choose one that is designed for use in colder environments. This will make it perfect for early spring weather. These microorganisms will live in your filtration media, so only wash it if water flow is restricted.

Getting Your Pond Ready for Fish

For the safety of your fish, you must prepare your water properly before you add them. During the first four to six weeks, you should monitor the ammonia and nitrite levels using a test kit. Once the test results indicate that the levels are safe, your pond is ready for fish. Start out by adding only a few small fish in the beginning to see how well they do before you add more.

Tip: Keep in mind that as your fish grow, they will produce more waste. A good way to help keep your water safe is to have no more than one inch of fish per square foot of surface area.