Aquaponics is the combination of aquaculture and hydroponics. Hydroponics requires expensive nutrients to feed the plants, and also requires periodic flushing of the systems which can lead to waste disposal issues. Re-circulating aquaculture needs to have excess nutrients removed from the system, normally this means that a percentage of the water is removed. This nutrient rich water then needs to be disposed of and replaced with clean fresh water. When combining aquaculture and hydroponics, the challenges of each individual system become beneficial to the combined system. Aquaponics can be simple or complex and vary in size depending on the system chosen, which is one reason why it can be implemented in an urban setting, where space can be limited.
The products produced in an aquaponics system are typically leafy plants, vegetables and fish. Green leafy vegetables and herbs such as lettuce, arugula, and microgreens have been shown to do well in an aquaponic system; popular fish breeds include tilapia, trout and catfish. In this system, bacteria in the water convert ammonia wastes from the fish into nitrates that can be used by the plants. The plants extract the water and nutrients they need to grow, cleaning the water for fish.
Advantages of aquaponics:
- Little soil is needed
- It is a largely organic process with no need for external fertilizer input or pesticides
- Farming can take place year-round
- The process conserves water
- Urban aquaponics centers could create jobs in cities
- Expensive start-up costs
- Needs constant monitoring
- Not completely a closed chain process, since fish food is a required input
- Energy intensive
The Massachusetts Ave Project in Buffalo, NY focuses on employing youth to work in the areas of Urban Farming and Aquaponics, Healthy Eating & Accessing fresh local food, Supporting local farms and businesses, Sustainable food production and Social Enterprise. They offer workshops to the public on these topics as well. (http://mass-ave.org/)
Sweet Water Organics is an urban fish and vegetable farm in Milwaukee, WI. They offer an online mentorship resource to engage learners in aquaponics (http://sweetwater-organic.com/).