Understanding the Nitrogen Cycle in an Aquarium

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Understanding the Nitrogen Cycle in an Aquarium

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If you want to create the right ecosystem and habitat for your tropical fish- including cichlids- it is important to understand the nitrogen cycle in your aquarium. While toxic levels of nitrogen in natural bodies of water is quite rare, it is a common problem in home aquariums and tanks. It often arises from overcrowding the habitat and overfeeding the fish, which causes nitrogen to build and pollute the water.

In nature, the nitrogen compounds transform from ammonia to nitrates, which are then used and synthesized by the plant life in the water. This nitrogen cycle naturally takes around three months to complete. In a closed environment like an aquarium, the process may require human intervention. The result of too many nitrogen compounds in the water? Nitrogen waste can be deadly for some species of fish.

So, how does the nitrogen cycle work in water? Here is what you need to know:

First Phase 

Don’t try to put too many fish in at first when setting up your new aquarium. Instead, only place a few hardy species in until you have a chance to monitor and assess the water readings. 

As you continue testing and evaluating the water readings in your tank, check for an ammonia level that is under .06 parts per million, or ppm. Test the water vigilantly until the ammonia level drops- at least every couple of days at first.

Two Weeks 

After a couple of weeks have passed, the tank’s ammonia levels should drop and be at 0.0 ppm. This is good- it means the nitrogen cycle is moving along. During this time, the nitrites level should increase, too- the cycle will be done when the nitrites reach 0.0 ppm.

Six Weeks 

Around the sixth week of the cycle, you should see a decrease in your nitrites level, while the nitrate level increase. Ideally, the nitrates should be somewhere around 25.0 ppm at this point in time. These are indicators that you are at or near the final phase of the aquarium’s nitrogen cycle.

Final Phase 

Your nitrogen cycle is completed when you have 0.0 ppm of Ammonia, 0.0 ppm of Nitrites, and >25.0 ppm of Nitrates. When this is achieved and the water in the tank is stabilized, you can go ahead and add more fish, or other aquatic life, to your tank over time.

Continue to test the water, at least weekly, but also anytime that it appears to be murky or cloudy, too. Know that every time you add more fish or species to your aquarium, it will temporarily impact your water readings.

Take care of your African cichlids- and other species- with these tips regarding the nitrogen cycle. It is integral to get rid of nitrogen waste to create a healthy habitat and aquarium- and to keep your fish safe from nitrogen toxicity.

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