One Friday on our lunch break, a few of us rode to Top Farmer’s Aquaponic research lab in Berlin. We’re a group of designers and technologists who’ve been enriching our understanding of systems design, in particular by looking at systems closer to the natural world.
What is aquaponics? Basically cultivating fish combined with hydroponics — sounds simple but those in the scene have spent years tweaking their systems with the holy grail of engineering an efficient system that is as closed loop as possible.
Its ancient roots go back to the Aztec chinampas — floating plant islands in canals and the South East Asian paddy fields that farm rice in combination with fish.
However, modern aquaponic farming is relatively new, gaining ground only in the 1970s. Backyard preppers saw the beauty of the system early. But lately, companies such as Whole Foods have begun to experiment to find out whether this kind of system could actually be a sustainable way to produce food for a mass market.
While the Top Farmers site we visited is in heavy research mode, they still regularly run tours to share knowledge on their findings. And so it was one afternoon that we walked off a busy road, and stepped through a gate into the compound where Top Farmer’s is co-located: A lush garden filled with miniature ponies, goats, chickens and beehives. Klaus was our guide for the day.
Top Farmer’s is finalising and testing their system and processes in order to step up to a 2500 sqm commercial farm next year — this site, like the research lab, will also be located in the middle of Berlin city. They expect in their first year to turn over 15 tonnes of food, but to do much more once their system is optimised.
How does aquaponics work?
Modern systems work by using the waste produced by the fish in the fish farm as a fertiliser to grow plants in a soilless system. The plants and a bacterial system together clean the water and send it back to the fish.
Benefits of aquaponics
Water-based plant production systems use significantly less water than soil-based systems and are lighter so for example, can be placed more easily on a roof. As it’s a controlled environment, pest control needs are reduced and there are more opportunities to optimise the system. No external phosphate is needed, and there are sustainability benefits in such local food.
Top Farmer’s see the commercial viability of their farm mainly through the fish they will sell, and possibly some exotic food plants. They don’t expect to compete in producing standard salad or tomatoes.
Step by Step
Klaus and some friends started Top Farmer’s on the roof of their apartment with 10 fish. After 2 years they made a bigger system and then found their current site, at a school, and organised to cooperate with them. Next year should see them in their 2500sqm commercial farm.
With aquaponics still an emerging field, Top Farmers has been and is running a number of experiments around:
- The seeds they use — avoiding Monsanto and using f1 hybrids — but trying to strike a balance between using these older varieties without as much fruit and still running as a commercial farm.
- Keeping low tech alternatives in mind — They’re aiming to have an alternative with the least tech possible so the system can be used in developing countries for food security.
- Testing substrates — Aquaponics uses substrates instead of soil to avoid the soil clogging up the pipes of the fish tank. It’s important that the substrate gets nutrients from the water and stores it. Their set up was baskets with each substrate, seeding the same salad in each and monitoring them over 3 months. Measurements were taken of the nutrients soaked up by the substrate. They also looked at how much the salad grew and measured the pH levels. Small but noticeable differences in the results have informed their substrate choices for different plants.
- Fish food — For Top Farmers, aquaponics and aqua culture is not the future until the fish food problem is solved. So long as they use fish to feed fish, they don’t consider it sustainable. But currently no alternative exists. They’ve sourced the feed with the lowest amount of fish powder in it (30%). The rest is soya which they’d prefer to avoid because of its rainforest source. Top Farmers is hoping a lobby group will grow in the next 10 years so that they’re able to get plant-based feed, or that the government will lift the ban that prevents them from feeding their fish with insects.
- The Rain Worm Filter: The rain water falls into the worm farm, and the worms excrete enzymes into the fish water, the enzymes work to strengthen the fish. Algae or snails can also be used in a similar system. This filter isn’t as productive as the plastic filtration, so the system does actually work without the rain worm filter but Top Farmers suspects that the enzymes help the fish.
Growing food for the fish spawn.
“But to be honest we’re a starting project so we can’t make everything good from the beginning. It’s step-by-step thing. I get a stomach-ache when I think about it, I know where the fish come from, how they’re processed but that doesn’t help me making it better so, we know what we’re feeding them but we’re hoping in the future that it’s going to change.” – Klaus, Top Farmers.
- LED Project over winter: To build an inventory of light spectrum recipes for each plant.
Sensors: The plans for their commercial scale greenhouse are ready. Monitoring is needed for issues like pump breakdowns.
- Sensors: The plans for their commercial scale greenhouse are ready. Monitoring is needed for issues like pump breakdowns.
The Bacterial Filter: This is where the magic happens. The plastic has a lot of surface area for the bacteria purely through it’s shape. The bacteria changes the ammonia of the fish’s dirty water into nitrate and that’s all that’s needed to make the fertiliser. There’s also a pump that aerates the water.
The one thing they have to introduce to the system are trace minerals like magnesium, iron etc. which doesn’t come from water or sunlight. 97% of what plants need comes from water, sunlight and air, 3% from fertilisers when you’re gardening.
Aquaponics at home
Aquaponic systems can work in any size, even goldfish with 2 basil plants. It’s common in America as a lifestyle hobby, but not so much in Germany. Though Klaus says that ‘some old ladies from East Germany’ come and tell him how they used to use their goldfish water to water their plants. Some companies have crowdfunded products so you can do it ‘like a toaster in your kitchen,’ Klaus told us, he seemed skeptical. See the links below for Top Farmer’s free instructions on how to build a small-scale system at home.
As the tour ends, Klaus shares with us his dream of lying in a hammock perched under a banana tree laden with fruit, soaking in the humidity of the greenhouse — all in the dead of a bleak Berlin winter.
The first chill of autumn is in the air as we step out of the Top Farmer’s greenhouse. As a couple of us contemplate getting one last ice cream of the year — Klaus’ dream of the hammock seems wildly fabulous — as do the possibilities and challenges of Top Farmers step-by-step building a system closer and closer to a closed loop.
Photos by Susanne Feldt, phone photos by Mei
- Top Farmer’s instructions to build a small-scale system at home
- To run the LED or sensor projects at Top Farmer’s, see more here
- Wholefoods financing the FarmedHere aquaponics site
- Fox, Bradley K.; Howerton, Robert; Tamaru, Clyde. “Construction of Automatic Bell Siphons for Backyard Aquaponic Systems” (PDF). University of Hawaiʻi at Mānoa Department of Molecular Biosciences and Bioengineering.
- Aquaponics section at the United States Department of Agriculture Online Library