Aquaponics

Aquaponics is the combination of aquaculture (fish farming) and hydroponics (growing plants using water rather than soil).

Introduction

Edible fish are grown in a tank. Their poop enriches the water with nutrients.
This enriched water is pumped into gravel beds with edible plants rooted in them. As the water flows through the gravel beds, the plants' roots and the bacteria that grow on the gravel take nutrients from the water. This both nourishes the plants and cleans the water.
The water, now clean, flows back into the fish tank.

The system provides fish, vegetables and herbs for people.

Feeding the fish

• Commercially available fish food is the most common way of feeding the fish in aquaponics. The disadvantage is that your system then requires constant input of resources.
• Algae will grow endemically in nearly any body of still water. Fish will eat these, but in practice it is not possible to grow enough algae to sustain an aquaponic system. You can increase the fraction of the fish's requirements met by algae by providing a surface underwater for the algae to grow on. (Remember when you had a goldfish as a kid, and the little castle in his tank got covered with green stuff?) Use something with high surface area.
• Duckweed, a high-protein, fast-growing pond weed, can be grown on the surface of the tank. There are species of duckweed adapted to nearly all climates.
• Worms from a compost heap can be fed to the fish. The worms can be fed with grass cuttings, food waste and other organic waste. Some of the compost from the wormery can be added to the water input to the gravel beds; this diversifies the nutrients the plants receive. Aquaponics combined with vermiculture is nearly a closed-loop system. Organic waste is converted into worms, worms into fish, fish into vegetables. The fish and the vegetables are converted into human life!

System design

A rule of thumb is that the volume of the gravel beds should be twice that of the fish tank. Gravel beds would typically be about 40cm deep.

Fish can normally be stocked at 2-3kg of fish per cubic meter of water.

The species of fish used depends on the climate. Choose fish that are adapted to the local temperature.

Water quality

Oxygenation

Most aquaponic systems require an air pump underwater. Having the flow from the

Open-source systems

• Farm Fountain, an open-source, inddor, vertical aquaponic system.
• Barrelponics - Aquaponics in a barrel.

Resources

• Aquaponics info at F.A.S.T.
• Backyard Aquaponics. Includes a thriving forum
• Growing Power a non-profit dedicated to educating people about growing food
• Friendly Aquaponics contains plans for systems
• Aquaponics Journal articles
• Wikipedia aquaponics article, Further Reading section
• Aquaponics Information at aquaponics.com
• Aquaponics on Appropedia