Backyard Aquaponics – A Sustainable Food Source

Aquaponics is about growing fish and vegetables in a productive and integrated system, suitable for backyards. In essence, aquaponics can be thought of as the merging of both Aquaculture and Hydroponics to create on sustainable system. Both of these have some downsides; hydroponics for instance requires nutrients and products which can be expensive in order to feed the plants, and also requires an ongoing and regimented “system flush” which can lead to waste disposal issues.

About Backyard Aquaponic Systems

Aquaculture (fish tanks) requires excess nutrients to be removed or “flushed” from the system. What this normally means is that on a day to day basis a certain percentage of water from the system is removed.  As a result of the water removal, the nutrient rich water then needs to be replaced with clean fresh water. Re-circulating aquaculture and hydroponics are already both very good methods of cultivating and producing vegetables and fish, but when we look at the the prospect of combining the two, these negative aspects are turned into positives and help to maintain the sustainability and efficiency of the systems.

Aquaponic Systems can be as complex or as simple as you wish them to be. The simple system that is pictured below is made from an Intermediate Bulk Container (IBC). The top of the container was cut removed and flipped upside down in order to become a growbed for the plants. Water is then pumped into the growbed from the the fish tank. From there, the water trickles down, travelling through the media and through the plant roots in the growbed before re-entering the fish tank.

As the water trickles down past the roots of the plants, they extract the water and nutrients that they require in order to grow. This also cleans the water for reentry into the fish tank. During the process Bacteria that are present and living on the surface of the growbed convert ammonia wastes that are a by-product of the fish into nitrates that are suitable for use by the plants. The term “the nitrogen cycle” has been coined in order to reference this conversion of ammonia into nitrates.

Common methods of growing plants in an aquaponics system include filling growbeds with media like gravel or even expanded clay pebbles Growbeds, however there are several other methods that may be used in order to have a successful system. In fact any method of hydroponic cultivation can be adapted or slightly modified for aquaponics. For instance floating foam rafts can be used in order to grow Plants, while Vegetables can also be grown using Nutrient Film Technique (NFT), or through various other “run to waste” methods of growing. This is accomplished by removing a certain amount of the fish water each day and watering the various other vegetables that are planted in different media such as coir peat, vermiculite, perlite etc.

The species of fish that can be grown in your aquaponic system are many, however local government regulations may affect your selection, so it is important to get any information about restrictions that may apply beforehand. Within aquaponic system, there can be a high stocking of fish while the amount of water used by the system remains low,  a result of the recirculating nature of the system. Research and tests have concluded that an aquaponic system can use about 10% of the water used to grow vegetables in the ground. Due to this and the various other benefits, aquaponic system can be incredibly productive, producing approximately 50kg of fish, and hundreds of kilograms of vegetables within 6 months in a system that takes up about the same area as your average carport, 8m x 4m.

This is a system that requires no bending, no weeding, no fertilizers, and only uses about the same power it takes to run a couple of light globes.

Alexandria Residence

Aquaponic Systems and CplusC

CplusC is currently exploring an integrated aquaponic system on a project in Alexandria. In consultation with our clients at the early stages of the design process we develop strategies which seamlessly integrate aquaponics into the building and landscape in order to deliver an innovative landscape feature which is both functional and elegant.