Aquaponics is the agricultural practice of growing plants and fish in a closed, re-circulating ecosystem.
Within a closed system, aquaponics recycles water which by many estimates reduces water consumption by 90% to 99%. This is because an aquaponic system is more efficient, such that the majority of the water in the system is directly used by the plants. In traditional agriculture, more water is used because very little of the water goes directly to the plant. Much of the water is lost to run-off, evaporation, and soil absorption not directly being used by the plant.
Aquaponics is a combination of both hydroponic and aquaculture methods.
This is the simplest approach to categorizing aquaponics, but as you'll see aquaponics is distinct from both hydroponics and aquaculture. Like hydroponics, aquaponic agriculture grows plants without the use of soil. This is possible because soil is not a necessary component for growing plants. In traditional, soil-based agriculture the soil acts as a reservoir for the nutrients required by plants to grow. In hydroponics, the plants pull nutrients directly from the water. However, there are very minimal nutrients in most water supplies. Therefore in hydroponic agriculture, it is often necessary for the nutrients to be added to the water using organic or chemical solutions. Typically, this chemical-rich water cannot be reused after it has been cycled through a hydroponic system and in many cases is actually considered toxic to humans and animals. In this case, the water should not be re-introduced to the environment. Admittedly, not all hydroponic production results in toxic water. The hydroponic industry has improved over the years and producers now have safer and more effective options to raise produce. Unfortunately, not every producer (whether hydroponic or traditional agriculture) has embraced environmentally friendly practices.
Aquaculture is a farming method used to raise aquatic species. This is done in a controlled water environment, such as large tanks, confined pools, and segregated portions in natural bodies of water. A variety of aquatic creatures that include fish, mollusks, crustaceans, and plants may be raised and harvested in these environments. However, the practice of aquaculture can cause of a variety of damage to the natural environment. High-density populations of fish result in high-density waste, which must be managed through cleaning, mitigation, or removal. In natural bodies of water, waste accumulation can upset the delicate balance of the aquatic ecosystem. In the worst-case scenario, the waste is not removed and the water becomes toxic to the fish resulting in a fish kill, where all the fish die. Additionally, there is ample concern about the introduction of invasive, non-native species into nature.
Both hydroponics and aquaculture on their own have challenges and require additional inputs for a single product. Hydroponics requires added nutrients and often results in an unwanted output (toxic water). While in aquaculture the burden of managing fish waste is tremendous, not to mention managing other potential environmental risks. In both methods, there is a single product, either a plant or a protein. Aquaponic agriculture combines the best of both worlds and leaves behind unwanted parts. In an aquaponic system, the fish waste in the water is cycled into grow beds where seeds or plants are growing. This fish wastewater provides the essential nutrients for plant growth and reduces the need for added chemical nutrients. In turn, the plants essentially clean the waste from the water and return it back to the system where it is re-used and recycled efficiently.
Aquaponics relies upon microbiological processes to foster the relationship between plants and fish.
While the above information provides a general picture, there is actually a lot of science behind the relationship between the fish and plants thriving together. A brief explanation is as follows; however, for a more technical discussion, we recommend you check out this peer-reviewed article. Ammonia is released by the fish waste, while high levels of ammonia would normally kill fish in an aquaponic system this ammonia is converted into nitrites and then into nitrates by naturally occurring bacteria that develop in the aquaponic system. Remember, not all bacteria are bad. In this case, the bacteria that occur naturally in this system are good bacteria and necessary for a thriving aquaponics system, much like many of the bacteria humans carry on their body are good bacteria that actually keep us healthy. The nitrates that result from this conversion process are then absorbed by the plants, which provide all the necessary nutrients for the plant to grow. The result of this natural process is clean water that provides a safe environment for the fish. Check out our graphic below.
Important things to know about the aquaponic cycle.
- The bacteria in an aquaponic system take time to grow and develop. How long it takes is dependent on the design of your specific system, the size of the system, water cycling strategies, and fish species. There are methods to assess the required time for bacteria development in your system, and we recommend that any aquaponics farmer plan for at least one month for the system to reach readiness before planting any valuable crops or using costly fish.
- The aquaponics cycle is ongoing. For lack of a better word, it is a batch at a time. It is a constant process that is naturally occurring at all times in the system. The water requires some basic monitoring to ensure that there is a healthy level. This can be done through water testing (which is recommended) and also experience. A seasoned aquaponics farmer will be able to look at crops and know if the water requires some adjustment. However, until you reach that point and are comfortable with the inherent risks (fish kills and loss of crops) we recommend regular water testing.
Information provided by Symbiotic Aquaponic.