They have moved from Brisbane to Manchester to be nearer their family and have been in the house since July 2009. In that time the house has gone from being an average home with a large garden to an extraordinary beginning in self-sufficiency (see the picture of the garden, right).
The garden has been the primary focus of the family's time and resources so far and now contains fruit trees, garden beds, composting and most impressively a polytunnel that houses an aquaponics system.
Aquaponics is a balanced system of food production that utilises a nutrient cycle (see picture of nitrogen cycle, below).
This picture is sourced from Backyard Aquaponics.
What this looks like practically is a one or more grow beds connected to a fish tank via pipes that circulate water with a timed pump.The scale can vary in size and complexity depending on the space and resources available. A balcony system might have a small tank with gold fish and a small herb garden while a system like Andrew's has a large tank for edible fish and many grow beds for herbs and vegetables that will feed the family of four. (See picture, left, for an example of a basic system - sourced from Backyard Aquaponics).
The grow beds contain media such as expanded clay or river gravel to hold the plants in place and the nutrient rich water from the fish tank then floods this bed at timed intervals to feed the plants, thereby cleaning the water to put back into the fish tank (Note, there are variations on the flood and drain methods such as continuous flow or floating raft. See websites below for more information).
Andrew hopes that eventually his system of grow beds and fish tanks will provide the family with all of their non-root vegetables and much of their protein. The family aims to close the loop in this system by feeding the fish using both what they grow and the worms and fly larvae that are naturally attracted to their compost. This is impressive from a sustainability perspective because it avoids the pitfalls of large scale commercial fish farms that often use wild fish to feed to the farmed ones thereby depleting the overall stocks and causing a dangerous imbalance in the ecosystem.
The Trafford Eco House system, a little more complex than a basic
one, has 6000 litres of water in circulation. The 3000 litre fish tank will eventually grow Rainbow Trout and three smaller tanks act as sumps. When water is pumped from the sump into the fish tank it causes the water level to rise and the overflow to be channelled via pipes at the top of the fish tank into the grow beds.There are three large grow beds down the middle of the polytunnel and five or six smaller ones along each side wall all using expanded clay (see picture, right). Once these are filled their overflow system drains the water, now cleaned of fish effluent, into the sump to wait for the next cycle.
At the moment the system is cycling water once per hour in order to build up the bacteria necessary to the nutrient cycle and to adjust the flows to each grow bed. Once this is complete the fish can be added and vegetables planted, either as seeds or seedlings. Andrew has planted some rocket seeds as an experiment and they are beginning to sprout (see picture ,left).Andrew's experience of setting up this system over the past six months has provided the following valuable lessons:
- Using large grow beds rather than many small ones requires less resources such as piping and the time spend installing it.
- Plastic tanks will buckle under the weight and pressure of water so need a good wooden frame around them. Andrew would consider using just a wooden frame and a plastic lining for a fish tank if he were to repeat the process.
- The foundations that the whole system is build on must be solid. Andrew has spent extra time and money on reinforcing the ground under the weight of the tanks and grow beds after they began to sink.
- The use of just one pump in the entire system is preferable. If many smaller pumps are used to pump water through the system and one fails this can cause flooding.
- Expanded clay is very effective at retaining moisture and the necessary bacteria but smaller bits can block pipes.
- Engaging local council in your activities can greatly expand the network of people who may show interest in this system and provide assistance in the future. The council promotes the Trafford Eco House and Andrew holds workshops on site.
I now understand that this technique can be made as simple or as complex as you like but it still remains low maintenance and low impact in terms of food production techniques. I can also see why this system has been so successful in Australia - in many areas of the country a polytunnel is not necessary because there is less temperature variation than somewhere like Manchester. A simple cover from the rain is all that might be required. And we can grow Baramundi because it is native (yum).
For me Aquaponics should be part of our eating future in Australia. I definitely want to make it part of mine.
Websites with useful information:
- http://www.aquaponics.com.au/ (Commercial, New South Wales based)
- http://www.backyardaquaponics.com/ (Commercial, Western Australia based)
- http://www.aquaponics.net.au/ (Commercial, Queensland based)
- http://traffordecohouse.wordpress.com/ (non-commercial)
- http://aquaponics.org.uk/ (non profit)
- http://www.uvi.edu/sites/uvi/Pages/Research.aspx?s=RE (University of Virgin Islands, Research based)
Huge thanks to Andrew and his family at the Trafford Eco House who so generously took the time to show Maureen and I around their home and garden.
Also, thanks to Charlie and Rebecca, who run Aquaponics UK out of Stirling University, for chatting to us back in January about their experience of aquaponics.
