Introducing aquaponics

Growing fruit and vegetables in the city is an increasingly important part of the food system. Localised food growing makes sense, particularly as rising food costs and an increase in extreme weather events threaten the current method of transporting food grown far away to our urban centres. Urban agriculture is one way to reduce food transportation and related carbon emissions, but traditional farming requires a lot of space, water and fertilizers. Growing food in the city requires some measure of ingenuity.


Robbie Kershaw and his family have 100 trout and a lot of fruit and vegetables growing in their suburban yard.

Aquaponics (a fusion of aquaculture and hydroponics) is a method of growing fish and vegetables sustainably by replicating the closed-loop nutrient cycle found in nature. Within an aquaponic system, fish and plants form a symbiotic living arrangement. Water from the pond is flushed through the soil-less plant beds where the plants filter the ammonia out of the water. Anyone who has had a pet fish will know that toxic build-up of ammonia in a fish tank is toxic for its fishy inhabitants. Given that ammonia is a complete fertilizer for plants, an aquaponic system is a water efficient way to feed plants and supply fish with plenty of fresh water.

Aquaponics is perfect for Australian conditions because it uses only 10 per cent of the water needed to grow vegetables in soil. It also requires only minimal inputs such as fingerlings (baby fish), fish food and a small amount of electricity to power a water pump, with any waste produced becoming an input for the system. There are ways to reduce these inputs further such as using solar panels as an electricity source and growing vegetarian fish species such as silver perch. You can even grow food such as duckweed for the fish yourself.


Aquaponics can be a productive use of small spaces. While aquaponics can be expensive to set up, there are some cheap and simple designs that make use of repurposed materials such as bathtubs or reusable containers, like this one at the 107 Rooftop Garden in Redfern, Sydney. Image: Milkwood Permaculture.

If the fish food is sustainably sourced, aquaponics could also help reduce pressure on wild fish stocks, already under great strain, as well as reliance on unsustainable fish farming.

You can find plenty of aquaponics advice online and there are many sites with open-source plans for DIY systems and forums for ongoing support. Not all websites offer sound advice though, so it pays to be selective. The number one rule is to be adaptable with your approach. There is no one right way to do aquaponics, every system will have unique quirks and styles.


Plants in an aquaponics system are grown without soil in a clay medium.

While accessible, aquaponics is not for the casual gardener. It doesn’t take an engineer to build a small backyard system, or a horticulturalist/aquaculturalist to run one, but it does require daily attention, persistence and patience.

Aquaponics is perfect for a resourceful person with plenty of gumption. Keeping your plants and fish healthy, and the technical components working requires time, but with considered design and carefully selected species, the right set-up can grow a fingerling into dinner in less than a year. And if the idea of eating the fish doesn’t appeal, you could opt for goldfish as pets instead.


Robbie Kershaw has been working with aquaponics for five years, but his love of fish is lifelong: “I have kept fish all my life,” he says, “It is my passion, and I’m a keen gardener, so it seemed like a natural progression.”

Robbie has one commercial and one DIY system on his 400-square-metre property; the prettier of the two in the front yard, where it attracts much interest from passers by, and the less aesthetically pleasing system is out the back. The system has about 100 rainbow and brook trout on the go but he sees the fish as secondary to the vegetables, which provide a year-round supply for the family and the neighbourhood.

– A budget of $500 should cover the cost of materials and fish stock.
– A good pump is crucial as circulation is the key to maintaining a healthy ecosystem. A pump costs around $100.
– Make sure the plant bed beads are non-concrete and non-porous, to avoid contaminating the water.
– The ongoing costs of fish food and power to the pump are offset by low water use and trout dinners.
– Aquaponics only requires low energy input, but solar power is an option to reduce related emissions of the system. However, it is crucial that the pump runs 24-hours a day to avoid killing the pH-sensitive fish. Robbie advises beginners start off with a mains-powered electric pump.

Sustainable Design Principles Event 2015

This event series is the brainchild of Emine Mehmet, Global Sustainability Ambassador and Interior Designer. The yearly event is aimed at engaging and educating the design and construction industry on sustainable design.

This year’s event focuses on the Dr Chau Chak Building at the University of Technology, Sydney. The keynote speaker is Danielle McCartney, Manager, Sustainability, UTS. The MCs for the evening will be Barry DuBois of The Living Room and Peter Colquhon of Better Homes and Gardens. A panel discussion will include Ray Favetti, Favetti Group of Companies, Cathy Inglis, Brickworks , and Stephen Giblett, Aecom. Visit the SDPE website to book your tickets.

Image: Hpeterswald – Own work. Licensed under CC BY-SA 4.0 via Commons

Make do and mend: passive solar upgrades

If your house was built more than 10 years ago, chances are it’s hot in summer and cold in winter. The truth is, the majority of houses in Australia, built long before energy-efficient regulations, are not really up to the job of keeping their occupants comfortable. With household energy use accounting for around one fifth of our emissions, over a third of this from space heating and cooling, improving on the existing stock has a wider imperative too.

There is little doubt that the best way to reduce your home’s impact is to reduce its need for heating and cooling, but where to start? The first thing might be to decide on the scale of the changes: is a massive renovation needed or could daily life be improved with some careful retrofitting for increased energy efficiency? Minimising the size of any extension will save money, and using minimal materials is the best way to reduce your project’s environmental impact, also resulting in less space to heat or cool.

Experts agree that your insulation and glazing choices are important ones. Up to 40 per cent of heat can be lost through windows and up to 87 per cent of heat gained through them, so the right windows and in the right place can make a big difference.

As heatwaves become more intense and frequent there are suggestions to reduce the amount of glazing to prevent conducted gains. An energy assessor can recommend specifically the right ratio of mass to glazing required for your building type and orientation, and is best consulted at the design stage.

For most places in Australia, low-cost heat-proofing measures such as ‘cooling’ your roof with high-albedo or white paint could also have a big impact. If the walls of the house are not well shaded from the west and east, consider ways of shielding these from radiant heat through landscaping or well-designed awnings and overhangs.

Sustainable design experts offer advice on making your home more energy-efficient.

People Oriented Design

Grun Eco Design

Sanctum Design