Aquaponics systems have grown in popularity over the years and they’re currently one of the most common urban farming techniques. But while closed loop gardens—including the one you see above —are becoming dime a dozen, Eric Mandu is creating smart, internet-connected gardens. Mandu is also the founder of Kijani Grows, an Oakland-based startup that not only builds gardens but is also developing a suite of programs to benefits schools and communities.
Aquaponics of course is the integration of hydroponics (growing plants without soil) and fish farming. Mandu’s particular system is a tray of plants set on top of a fish tank. It’s a symbiotic loop that revolves around fish, bacteria and plants. Mandu’s only input is giving the fish food, which, naturally turns into waste. A pump system circulates this poop-laden water back onto the plant tray, where there are some rocks covered in bacteria that break down the fish waste into nutrients for the plants. Finally the plants absorb the nutrients and they in turn create oxygen for the fish.
Beyond creating a simple aquaponics garden, Mandu has also developed his own array of Linux computer-powered sensors that help him micromanage his miniature farms. Mandu says that with these sensors he’s able to track things like the water level or current temperature in the multiple gardens he has set up away from his West Oakland office at American Steel Studios. From his computer, Mandu was able to manage one garden with extremely large 600 gallon fish tank in San Mateo and then check on another system in a Guatemalan school.
Although Kijani Grows is already selling its Aquaponic systems through its website, Mandu’s main focus for now is to introduce $50 smart gardens to more schools around the world so he can collect more data. Eventually this network of aquaponic systems will become a platform that allows schools to exchange experiments. This way the students can share data and the kids can learn from one another.
Just one of the things that have come out of Mandu’s research is he noticed a problem called fish kill—this is where a large group of fish die at night in rivers and ponds. According to the data, it only happens in the fish tanks at a certain time of night, temperature, and only in the summer time. On top of noticing the problem, Mandu has also been able to reproduce the same conditions in his fish tanks. The next step of course is to create a solution to prevent it from ever happening in the first place.
Eric Mandu speaking with Karen Cusolito, the American Steel Studios Founder
Taken outside of his small gardens though, Mandu believes his sensors could be used to help even more people.
“One application of [the sensors] is gardening but I could very easily take my sensor array and put it into a river or a lake or other places that I can really start telling people okay we’ve seen this happening over and over again,” Mandu told us. “This means your fish are about to die or the plants need more water.”