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Understanding the Nitrogen Cycle

Understanding the Nitrogen Cycle

A well-balanced ecosystem in a pond is the perfect environment for plants and fish to thrive. Creating and maintaining this ecosystem is easy once you have a good understanding of the basics. In this article, we will discuss the nitrogen cycle and why it is important to all aquatic life in a pond.

Nitrogen Cycle 101

The nitrogen cycle in a Koi pond is responsible for biological filtration to keep the water at safe levels to support aquatic life including fish and plants. Without an established ecosystem, high levels of ammonia and nitrites can put fish into danger.

Once a pond is installed, nitrogen from the atmosphere enters the pond through rainfall, wind and runoff. Leaves, twigs and other debris may also enter the pond. In mature Koi ponds, fish waste and uneaten fish food will also add to the debris and it will start to decay overtime with the help of beneficial bacteria or microorganisms called nitrosomonas and nitrobacter. As the debris breaks down it releases ammonia into the water. Nitrosomonas will reduce the ammonia and oxygen levels in the pond by consuming them and produce nitrites. Nitrites are also harmful to Koi so another organism called nitrobacter will reduce the nitrites in the water and convert them to harmless nitrates. The nitrates are then reduced by water changes or consumed by aquatic plants and algae.

New Pond, New Bacteria

Nature takes time to establish an abundant population of beneficial bacteria, nirosomonas and nitrobacter, so when a pond is first started, you may want to wait four to six weeks before adding fish as the ammonia and nitrites levels will be high.

To help increase the number of beneficial microorganisms, seed your filter media with sticky bacteria like Pure+ Filter Start Gel or PL Gel, and add Nature's Defense to the water. Boosting dissolved oxygen levels in the pond can also be helpful with a simple Aeration Kit.

Maintain Bacteria Levels

In the early spring when established ponds are waking up after a long winter, a similar cycling process will take place. Some nitrosomonas and nitrobacter will survive in your filtration media and gravel and begin to colonize, but it's a good idea to give them a boost. Seasonal Defense is formulated for use in cooler temperatures – making it perfect for early spring applications. Since those microorganisms live in your filtration media, avoid washing it unless water flow is restricted.

Cycled and Ready for Fish

Prepare your water before adding fish into your pond to keep them safe. Throughout the first four to six weeks, monitor ammonia and nitrite levels using a master test kit. Once the test indicates that your levels are safe, the pond is ready for fish. Start by adding only a few small fish at first to see how well they do before adding more.

Pro Tip: Keep in mind as the fish grow they will produce more waste, so to keep your water safe, allow 1-2 koi or 2-3 goldfish per 200 gallons of water.