​​Yiannis Trisevgeni welcomes us on a nice sunny afternoon. As a wanabee-farmer from the city, he as quite a unique way to grow plants: on his Appartement building's roof in the Petralona borough. He also owns a tiny bit of land in the inner suburb.His dream: to reach food autonomy.

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Once we're up there, not only do we get a gorgeous view down the city but we find ourselves into a green garden. Next to the lush trays where the plants grow, lies a strange pond. Yiannis grows his fruits and vegetables using a peculiar system: aquaponics.
 

Aquaponics is different from hydroponics; it's a closed system which doesn't require external inputs. It’s an imitation of nature, including a fish tank, plants for photosynthesis and micro-organisms (bacteria). This system has been known for 4000 years (Aztecs, Ancient Egypte, Australia) but it’s now little used.

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Everything starts (and ends!) in the fish tank which feeds the plant trays through 2 pipes + filters. The fish's waste dissolve and become ammoniac. Clay marbles at the bottom of the tray help maintain the micro-organisms. Those bacterias turn ammoniac into nitrate, which helps the plant grow.

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This whole system is easy to do on your own and it’s cheap thanks to up-cycled material. Yiannis only bought the air pump, the pipes and the clay marbles.

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Before you get started you should however get some education in fish farming because you’ll need to monitor the fish reproduction to avoid degeneracy problems. Also some chemistry basic to make sure the ammoniac levels don’t turn into to much nitrate.

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This system is economical and ecological since it requires far fewer water than a traditional land agriculture. Fully organic agriculture, easily adaptable to any context, especially small surfaces, it is a closed up and autonomous system : the pump relies on solar panels. Which allows for a more laid back style of farming where you can risk going on a holiday without risking finding your vegetable burned down...

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So he could be able to confront and prove the value of aquaponics, Yiannis has been experimenting with aquaponics as well as traditional agriculture for 3 years. From his various tests and observation, he’s come to the conclusion that aquaponics: require less water, and work. He also noticed that you can plant very close-apart so it takes up less surface. This technique is very suited for growing salads, purslane, herbs (basil, mint…) and root-type vegetables (radish, beetroot). According to him, the taste is clearly improved in aquaponics. Growing flower plants is also suited to this technique but in that case you should throw some magnesium and calcium in to the mix. Natural minerals of course...

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