Skip to main content
A Magazine for Sheffield

Aquaponics: Saving The World With Fish Poo

Have you heard scientists, planners and other extremists banging on about 'resilience' recently, often in contexts where we previously talked about 'sustainability'? Sustainability is about ways to organise our lives so that we won’t run out of food or melt the ice caps. Resilience is our capacity to bounce back from stresses, strains and shocks. Why the change? It has become more and more obvious that digging up trillions of tons of grungy, carbon-rich gunk and burning it is going to change things a wee bit here and there, so we all started looking for more sustainable paths to take, and many have been found. The tricky thing is that 1,500 massive corporations control 80% of global production. There's no short-term profit in saving the planet and our market-driven system has no mechanism to change tack. Even scientists are starting to notice this, and more and more are now working on resilience. A society is resilient if it can supply its needs - for example, for food, shelter or health - without relying on systems outside of its control. A society is not resilient if it relies on shipping in large parts of its needs from half way around the world. How can we increase the food we grow locally without creating pollution or using scarce resources like oil? Aquaponics brings fish and vegetables together in a symbiotic growing process. The fish produce nutrients that are used by the vegetables in a virtuous circle. The result is high-density food production that can be done at scales from the back garden greenhouse to industrial warehouses. It works well in urban spaces or on land suffering drought, pollution or soil depletion that is otherwise difficult to farm. It produces both fish and vegetables, reducing the load on our over-exploited and polluted oceans. And if you’re vegetarian, use goldfish or koi carp instead of edible varieties — they poo just as well. Year-round growing is possible even in climates like sunny Sheffield. The recirculation and biofiltration of water performed in aquaponics systems can reduce load on agricultural water sources, in contrast to both hydroponics and soil-based growing. The only input to aquaponics systems is the fish food and sometimes something like ground eggshells to help regulate the water pH. If you feed your fish on organic hemp seed, for example, or grow fly larvae in your food waste compost bin, then you know exactly what has gone into all the food you produce. We can grow bio-organic food without additives and, because we’re not using soil, the need for pesticides and the like is reduced. In fact we can’t use pesticides, or we risk unbalancing the aquaponics ecosystem. Increases in local food production promise to reduce carbon transportation costs and promote community resilience in the face of supply chain interruptions or economic shocks. Aquaponics relies on a continuously balanced ecosystem of fish, veg, bacteria (which convert ammonia to nitrates for the plants) and worms (which help break down solids in the fish poo). Sustaining the balance of this ecosystem can be complex, and setup costs and energy usage are also an issue. The Resilience Food project at the University of Sheffield and the Aquaponics Lab involves open instrumentation and control systems for aquaponics. These systems aggregate their data via the cloud to create virtual communities of growers whose shared experience reduces complexity and promotes take up. Everything is open source and free for all. In parallel, we’re working with recycled materials to bring down costs of construction and setting up measurement experiments so that we can say exactly what it costs to grow different types of crops in a Sheffield climate, for example. Want to join in? Get in touch. There are lots of reasons to grow as much food in our local areas as we can. If we become locavores, eating local as much as possible, we can start taking control of the content of our nutrition and reducing intake of the salt, sugar and preservatives that are driving diabetes and heart disease. Small farms have long been known to be more efficient growers than megacorp agriculture in terms of quantity of produce per square metre of farmland. This is not as paradoxical as it sounds. Small growers often bring greater local expertise and longer working hours to their agriculture on the one hand, and on the other big agriculture produces not just millions of Tesco lettuces, but also huge profits for shareholders, which have to come from somewhere. Aquaponics is a perfect partner for vertical growing systems, with water trickling down though rooting materials made from recycled plastic bottles, for example. The more biodiversity we have in our cities, the more we can make them a welcoming environment for everything from bees to butterflies, sparrows to sunflowers. And maybe we’ll get a bit more resilient in the process. )

Next article in issue 94

More articles