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What is aquaponics?

 Aquaponics combines the principles of aquaculture and hydroponics, without the use of chemicals or discharging nutrient pollution into the environment. Features include:

  • 10% of the water usage of a conventional garden.
  • Up to 5 times the plant growth rate of a conventional garden.
  • Fish and yabbies are also a food output but probably quite modestly for us.

It is actually a very simple, and very natural system – fish, invertebrates, nitrogen cycling bacteria, plants and people working in a relatively closed system. In our system (see below), the ~2,000 litre tank will hold fish (and an aerator); the water (with the fish waste) will cycle through grow beds in re-used bathtubs; the gravel in the bathtubs will develop a community of bacteria that convert ammonia from fish waste into nitrates that are absorbed by the plants; clean water will return to the fish. The water goes around and around by way of a 12v pump. Inputs are fish food, that we will produce ourselves as much as we can, and the outputs are vegetables and herbs (with maybe a few fish and yabbies). While various components are often thought of in isolation, the great elegance (and engaging fascination) of aquaponics is that involves the management of a complete, albeit miniaturised, ecosystem. 

As a food production technology, it is relatively new and has enormous potential in a world with diminishing per capita access to water, soil and individual land tenure. All things being relative, these are things that affect many of us a gardeners at RCOG as well as being concerns of ours at a global scale.

The RCOG Aquaponics Group

The aquaponics group perhaps best modeled on the Chook Group, but perhaps more broadly integrated with other garden parts. The group will be involved in managing the system as a communal resource for all members. To do this we might focus on the production of herbs and leafy greens to be enjoyed by all garden members, but will need to decide this as a group to balance return for those putting in the work with the wider common purpose.

 In terms of fish production, we ought not envisage a feast, but hope that in time we will get to enjoy some at communal Garden events. To this end we hope to include some (bound for the barbecue) yabbies in the system. The main job of our animal partners is however for them to be part of our ecology and to excrete.

 The generation of food for the fish may involve growing duckweed for them to eat, some harvesting of compost worms and the introduction of black soldier fly larvae production. If we take on black soldier fly larvae production we should try to share the work and the outputs with the chook group.

 The system will rely on our existing solar generated 12v power system to pump water through it (Serendipity #3 given that we only quite recently have it through some great previous efforts by members). Because of this, it will be located next to the shed to access that power.


An additional role of the aquaponics system will be education – for ourselves and for the wider community. For those getting involved, you are warned that when people get into it they often get way into it. In a few square metres we will have a microcosm of the sort of approach to environmental engagement and food production that lies at the heart of our ethos: in which what we do is part of a diverse ecosystem; where in a little piece of local we play out a global challenge. The things that we learn should not only engage us but be worth sharing with our wider community, because it can and will put fresh herbs and greens within reach of more kitchens and more meals, particularly for those with little or no garden and without adequate skills, interest or time for conventional soil gardening (i.e. a lot of people in eastern Sydney).


 Cordelia and Callum are looking at the toxicity of parts of the system. We want to run as clean and healthy a system as possible. We’ve decided to use fibreglass grow beds (old bathtubs) as they appear to be the least toxic of the bathtub materials.

 Power needed

 Ryan and Alla are looking into pumps.

 Introductory Resources

 For those who feel a twinge of interest, the following online resources, largely from the Milkwood aquaponics course notes:

Matt and Shannida - Aquaponics Australia

Practical Aquaponics
Murray Hallams site where you can get his dvd "Aquaponics made easy"

Costas's episode on Aquaponics which shows Murray's kit in Action

Backyard Aquaponics: a great site and forum dedicated to Aquaponics

A list of plants successfully grown by people on the above forum

Nice animation from Ecofilms showing how a Bell Siphon works

Black Soldier Fly