Lessons from the Aquarium – The Nitrogen Cycle

Lessons from aquariums that can fix the dead zone in the Gulf of Mexico

While I am going on and on about how Aquaponic farming is going to be the most cost effective and generally beneficial way to resolve the pollution problems which are causing the Dead Zone in the Gulf of Mexico and pretty much every fishery near the mouth of a river, I sometimes forget that most people are not ecologists, aquaponics enthusiasts, or aquarists. Because of this, my solution can sound too simple, and unlikely to work. So today I am going to explain the process that will make this pollution clean up work, and while discussing it maybe I will point out a few things that can help other aquarists and aquaponic enthusiasts develop their systems to be more effective.

First we will discuss the basic principles of the nitrogen cycle.

The nitrogen cycle primarily revolves around the transformations of nitrogenous compounds, primarily ammonia (NH3), nitrite (NO2-), and nitrate (NO3-). These compounds are produced as waste products by fish, uneaten food, decaying plant matter, and other organic debris within the aquarium.

1. Ammonia Production: The cycle begins with the production of ammonia through the excretion of waste by fish and other organisms, as well as the breakdown of organic matter. Ammonia is highly toxic to fish, even in relatively low concentrations, and can lead to stress, illness, and death if not promptly removed from the water.
2. Nitrosomonas Bacteria: Beneficial bacteria of the genus Nitrosomonas play a vital role in the nitrogen cycle by converting toxic ammonia into nitrite through a process known as nitrification. Nitrosomonas bacteria oxidize ammonia as an energy source, converting it first into nitrite in the following chemical reaction:NH3 + O2 → NO2- + 3H+ + 2e-
3. Nitrite Accumulation: While nitrite is less toxic than ammonia, it still poses a threat to aquatic life, particularly in higher concentrations. Nitrite interferes with the ability of fish to transport oxygen, leading to suffocation and other health issues if present in excessive amounts.
4. Nitrobacter Bacteria: Another group of beneficial bacteria, Nitrobacter, further processes nitrite into nitrate in a process called nitrification. Nitrobacter bacteria oxidize nitrite, converting it into the less toxic nitrate through the following chemical reaction:NO2- + H2O → NO3- + 2H+ + 2e-
5. Nitrate Accumulation: Nitrate is the least toxic form of nitrogenous waste and can be tolerated by fish and other aquatic organisms in relatively high concentrations. However, excessive nitrate levels can still lead to health problems, such as reduced growth rates, impaired reproductive success, and increased susceptibility to diseases.
6. Nitrate Removal: In natural ecosystems, nitrate is removed through various processes, including uptake by plants, denitrification by specialized bacteria, and dilution through water exchange. In aquariums, regular water changes and the presence of live plants can help control nitrate levels. Additionally, some aquarists employ specialized filtration media or denitrifying bacteria to further reduce nitrate accumulation.

It’s important to note that the nitrogen cycle is a dynamic process that requires time to establish and stabilize in a new aquarium. During the initial cycling period, ammonia and nitrite levels may spike as beneficial bacteria populations gradually colonize the aquarium and establish themselves. Monitoring water parameters regularly and taking appropriate measures, such as partial water changes and the use of bacterial supplements, can help mitigate any adverse effects on fish and other inhabitants during this period.

Overall, maintaining a healthy nitrogen cycle is essential for the long-term success of an aquarium, ensuring optimal water quality and the well-being of its inhabitants. By understanding and managing the nitrogen cycle, aquarists can create a balanced and thriving aquatic ecosystem for their fish, plants, and other organisms.

The next thing we want to talk about is how this applies to cleaning up our rivers.

I am sure that your first thought on this is something about how this is a natural system, and it is already happening. Which is true. The thing is, the rivers have grown and evolved to process the animal waste of the animals that would normally be around them. That is all still there, but we (farmers, consumers, and property owners that fertilize) add 100 times the waste levels that the river normally would process through run off an other ways.

Which is how aquariums showed me the answer. When you keep aquariums, you have a closed system. Which means you have to create and maintain your own nitrogen cycle for the health of your fish. This is done through using substrate to grow beneficial bacteria, artificial aeration of water to off gas, mechanical filtration, and more skilled aquarists will add plants to the system. Even then, except for the most skilled aquarists, regular water changes take place to remove the waste that your systems cannot.

The system I would propose would be the equivalent of adding deep substrate, aeration, mechanical filtration, and a large number of plants to an aquarium WITHOUT adding additional chemistry to the mix.

Basically we want to pull dirty water from the river, push it across tanks filled with rock and air stones/pumps to mineralize, and aerate the water. The rock surfaces and oxygen rich water will also provide lots of surface area to breed the beneficial bacteria that will process the ammonias to nitrites and then nitrates so that the plants can take them up.

From there we will use the nitrate rich water to feed the plants we are farming for our benefit and return the cleaner water to its original source.

This system will not reduce the water to nothing but H2O. There will likely still be many chemicals remaining that the plants are unable to take up, either because of excess volume or the chosen crops inability to utilize them, but there will be substantially less of them. But nature doesn’t need us to do its job for it. It just needs us to clean up after ourselves some and give a little help