Circular logic

Ever wonder where trendy eateries get their micro-coriander? It could be Unit 84, Britain’s biggest aquaponics farm, a self-contained ecosystem that’s set to produce 20 tonnes of salad and 4 tonnes of fish in its first year. Rachel Walker takes a tour with co-founder Kate Hofman.

I’ve looked into the future of (a kind of) farming, and it’s set on an industrial estate in Beckton, not far from London’s City Airport. The scenes are a far cry from picture-book pastoral as I wind past Canary Wharf and through the Blackwall Tunnel to the capital’s concrete outskirts. It’s still 10 miles to the M25 and the greenbelt beyond when I pull into an industrial estate and heave open the door to Unit 84: the biggest aquaponics farm in Britain, run by sustainable urban farmers, GrowUp.

I’ve seen aquaponics in action before. It’s a neat idea, a system that yields both fish and fresh greens in a self-sustaining, circular food chain: farmers feed tanks of fish, which produce nutrient-rich waste, which is pumped straight to the roots of hydroponic plants, which purify the water that’s pumped back into the fish tanks – and so on, round and round.

But the aquaponic projects I’ve seen before have been small-scale experiments. Not so Unit 84. GrowUp only started farming there in September 2015, but it already reckons its first year of production should yield about 20 tonnes of salads and herbs and 4 tonnes of fish. It’s building up a growing client base too, including Farm Drop, a local producer home delivery service, and east London restaurants such as Eat 17, Rosa’s Thai and the Good Egg.

Commercial viability is vital and that means scale, explains co-founder Kate Hofman. GrowUp launched three years ago, but their first project – an aquaponics scheme in a shipping container – was very much a pilot. Its purpose was to explain the concept, get backers and raise funds, says Kate. “If we farmed it intensively then we might have seen returns after eight years,” she laughs. But as a stepping-stone to help GrowUp secure its 6000 square foot space in Unit 84, it was a complete success.

“The plan all along has been to validate the business model and then scale up,” says Kate, who was a consultant at IBM before going on sabbatical to take a master’s degree in Environmental Technology. When she returned to work, she only lasted a few months, before handing in her notice and founding GrowUp with Tom Webster, a biologist with a master’s in Urban and Sustainable Cities. There’s no whimsy or idealism surrounding their plans. “We were always interested in commercial scale,” says Kate, reeling off percentages, forecasts, business plans and backers.

When the team got the keys to the site last May, they started straight away installing ducts to control temperature, humidity and air flow, and dividing walls to split the unit into separate rooms for the aquaculture, hydroponics and packaging. “The blank canvas of an industrial warehouse meant that we didn’t have to plough lots of money into a funky building that needed a lot of work,” she says. “The location was perfect too, because we can deliver to central London very easily.”

Each day follows a tight schedule of seeding, farming, packing, fish husbandry and managing pests without resorting to chemical fertilisers. “That usually means we bring in bugs to eat bugs,” Kate smiles. There are only 12 staff in total here, but it feels like more: the farm is laid out to maximise growing space, so there is a constant buzz of activity as people busily shuttle back and forth, squeezing past each other in the tight walkways.

Like lots of other aquaponics projects, GrowUp uses tilapia – around 400 fish per tank. Tilapia’s ability to thrive in densely packed environments is part of the appeal. Kate explains that they actually behave better that way: reduce the numbers to give the fish more space and they can become quite territorial and aggressive, she says. The other appeal is the food conversion rate. While salmon need to be fed 2.1kg of fishmeal to produce 1kg of meat, tilapia will produce the same on around 1.3kg to 1.7kg.


As a result, tilapia is one of the most commonly farmed fish worldwide, but it hasn’t always had a good press. “They’ve got a bad reputation,” Kate admits. “Sadly farming conditions often aren’t very good, so they can be associated with a muddy taste.” The conditions are as clear as a whistle here, however. There is a loud whir from the bio-filter pumping the nutrient-rich fish waste next door, and stark light bouncing off the laboratory-white walls. It feels foreign, but there isn’t so much as a speck of mud anywhere.

Next door, 10 rows of growing beds line the walls, and a scissor lift in the corner allows the farm aids to inspect the very top bed, 5.5m up. Each tray contains a different crop: nufar basil; holy basil; Thai basil; kale; pea shoots; micro-coriander; and sunflower shoots. “We’re the only people processing these shoots in the UK,” says Kate, explaining how she took inspiration from a Canadian farm. “They’re great to snack on, so crunchy.” To maximise shelf life and minimise damage, the greens aren’t washed or processed on site: they’re simply cut, packed into punnets and sent to customers around London.

At the end of the tour, we hand back the white lab coats, throw away the disposable blue boot covers, and return to the visitor’s centre, blinking as we leave the bright UV lights and return to a room that feels quite dim by comparison. The tour is a million miles from the mud and wind of most farm visits. I wonder whether such visits will, perhaps become a distant memory: should shepherds and cattle farmers be scared?

“They should be,” says Kate, matter-of-factly. “But not because of aquaponics, which isn’t a direct competitor. If we leave the EU then we will lose a lot of subsidies, which will put plenty of people in trouble.” Longer term, there’s also the argument that, in an ever more resource-hungry world, red meat is just too greedy. Unit 84, by contrast, is almost clinically efficient, although Kate is eager to point out: “It’s not all automated robotics. We still rely on human judgement and interaction.

“But the thing about technology is that, when used right, it optimises what you do best – and what we do best is grow salad.” For all the appeal of traditional agriculture, Kate presents a compelling argument. As pressure on resources continues to grow, perhaps the starkly different future that aquaponics presents will be here sooner than we think.

Share this article

    Related posts

  • Vietnamese fried tilapia

    The tilapia here has a crunchy, crispy skin and soft flesh, complemented by crunchy and sour unripe mango. This is a meal that leaves you wanting more and more, says Uyen Luu.

    read more

  • Tilapia

    Extensively produced around the world, tilapia is considered to be one of the most sustainable of farmed fish, and is usually available at Billingsgate Market, come rain or shine.

    read more

  • Grow your own

    A clever inner-city experiment in the heart of hip Dalston, FARM:shop is local café, urban farm and London’s biggest aquaponics scheme, all in one.

    read more