Aquaponics is the combination of an aquaculture system and hydroponics.

In aquaponics, one grows plants and fish together in an integrated system. The fish wastes provide a food source for the growing plants and the plants roots provide a natural filter for the water the fish live in. This can create a sustainable ecosystem where both plants and fish can thrive.

Aquaponics can be one answer to a fish farmers problem of disposing of nutrient rich water and a hydroponic growers need for nutrient rich water.

However for the system to work properly there must be a balance between the food fed to the fish, the fish size and density and the number and size of plants.

Generally the plant biomass is considerably greater than the fish biomass. In addition the plants may require additional foliar feeding to make up for some elements lacking in the fish waste water.

To make up an aquaponics system a water reservoir is required to hold the fish and crustaceans and this water is then passed through a plant system before it returns to the water reservoir.

For a home hobby system people often use recycled plastic containers to hold the medium for their plants. These plastic containers can be linked together using special rubber grommets that allow standard irrigation fittings to be used.

A hole saw is used to drill the correct hole in the plastic then a top hat grommet is pushed into the hole the poly fitting is pushed into the grommet and pvc or poly tubing pushed onto the fitting.

The best size to use for aquaponics is the 25 mm size as this allows faster drainage than the 19 mm or 13 mm or 6 mm sizes more commonly used for hydroponic applications.

For a small hobby system the first consideration is the size and location of the water reservoir. Fish and crustaceans do not thrive if the water temperature fluctuates so you need to consider insulating the tank and keeping it away from direct sunlight. Work on having no more than 1 kilogram total weight of fish per 1,000 litres of reservoir water. A reservoir that has a diameter depth ratio of 3 : 1 will help with surface gas exchanges but some aeration will be appreciated by the fish as will about 10 cm of washed river gravel spread over the base of the tank.