Aquaponics is an innovative agricultural field. This is a field in which innovation and hands-on practice will benefit you greatly. If you have questions or concerns regarding anything from water transportation to seedling care, reach out to fellow growers! Aquaponics is a growing field and the internet is full of experimental forums and startup companies.
Aquaponics is a combination of aquaculture (fish farming) and hydroponics (a method of farming that replaces soil with nutrient rich water). This nontraditional farming method is ideal for any urban farmer. Once a system is set-up and the nitrogen cycle kicks in, the only addition to the system is fish food. Aquaponics is also not restricted to the amount of space a person has, as models range from countertop devices to large greenhouse enterprises.
The backbone of aquaponics is the nitrogen cycle. Nitrogen is the most important nutrient for proper plant growth. Fish waste (ammonia) contains large amounts of nitrogen for potential fish food. Microbes that build up in the system break down ammonia to form nitrates, which plants uptake as food. The uptake of nitrates not only feeds the plants, but filters the water, which once returned to the tank, creates an ideal environment for the fish.
The microbes mentioned in the above picture are formed over time once the system’s water is cycling. The amount of bacteria in a system is directly associated with the amount of biological media in the aquaponic system. This media acts as a “home” for the bacteria as well as a substrate for roots to secure themselves on.
Biological media is any material that is porous and provides a surface area for bacteria to grow. This media replaces the dirt in a traditional farming system. The most commonly used media is hydrocorn (expanded clay pellets), others have used deer fencing, bio-balls, or any innovative substrate.
Ammonia is released from fish gills as (NH3), which can ionize and become ammonium (NH4). The two forms combined are known as total ammonia nitrogen (TAN). Ammonia is toxic and in greater quantities at higher water temperature and higher pH. The ideal concentration of ammonia in a system is 0 mg/L and if it exceeds 0.5 mg/l fish death can ensue.
Nitrosomas sp. converts Ammonia Nitrogen to Nitrite
This form of nitrogen is toxic to fish (>0.2 mg/l) and in a healthy aquaponic system should be 0 mg/l.
Nitrobacter sp. converts Nitrite to Nitrate
The concentration of nitrates can be much higher because this form of nitrogen is tolerable by fish. Plants uptake nitrate, and if there are high levels of nitrates (>50mg/l) more plants can be added to the system.
The main objective of an aquaponics system is to strike a balance between fish and plants. This balance begins and ends with the quality of water. In order to get nutrients bio-available for the plants fish need to be fed. The feeding of the fish starts a chain reaction. Once fish begin to eat it boosts their cellular respiration rate. As fish metabolize they take oxygen and turn it into carbon dioxide. The food they eat turns to waste (ammonia); this waste is a source of nutrition for microorganisms.
The most common fish used in aquaponic systems are tilapia. Tilapia are used because they require very little maintenance and can double as food. However, aquaponics in the northern hemisphere may not provide an ideal setting for tilapia. Tilapia are tropical fish and require warmer water temperature to survive; to grow tilapia one must heat their fish tank. This will add to the overall cost of a system. Trout are a cold water species that have been used in cold water systems; however, trout are not as resilient as tilapia and require pristine water quality with little to no fluctuations.
If one is focused primarily on growing vegetables from a system, then goldfish or koi are the perfect fit. These hardy, cheap fish will provide a large amount of waste at a very low maintenance level. Remember an aquaponic system is an ecosystem; do not be afraid to incorporate different species of fish that are different trophic (feeding) types. Increase the biodiversity and overall tank health by adding other aquatic species such as snails and shrimp to help break down waste into smaller solids.
Common Aquaponic Species
Generally, leafy greens and herbs do best in young systems. Many species of these types of plants tend to be resilient in aquaculture systems and require less energy than flowering or fruiting plants. It is important to do thorough research on which plants agree with this method of farming, not all plants will take to aquaponic farming.
Commonly grown produce is basil, mint, oregano, parsley, mustard greens, kale, swiss chard, etc.
Like traditional farming, aquaponically grown plants will experience deficiencies. Adjusting the level of nutrients in a system can solve these deficiencies. There are several online resources to compare plant to examples of common problems.
A mature aquaponic garden cannot be built in a day. Users must take time to ensure all fittings, filters, trays, and tanks are fitted properly and can handle running water with no leaks. The success of an aquaponic system is directly related to the time dedicated to the project. There is nothing better than physically inspecting the system on a daily basis. A relationship will develop between the ecosystem and the gardener.
Please contact us with any questions or concerns you may have about aquaponics! (We love talking about it)
Email us at: BigFish@bfiaquaponics.com