Aquaponics ​

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Aquaponics is a revolutionary type of horticulture. Essentially, it adds fish-breeding to hydroponics (aquaculture + hydroponics), inspired by traditional forms of agriculture such as that of the Sawas of Southeast Asia and the Chinampas of the Meso-Americas. It is an example of a closed-loop food system. The fish excrement supplies the fertility for plant growth, and the fish are fed with food scraps and insects grown in compost (e.g. soldier flies). If the fish are bred for consumption, it theoretically doubles the production of total food (calories) per m2 as compared to the two growing systems operated separately.

There are many variations of aquaponics, such as floating raft production, or on a substrate with flood and drain irrigation. We choose vertical gardening with buckets, in which the water from the fish tank runs through the pebbles in the buckets from the top downwards, and back into the fish basin.
The solar pump works during the daytime for 15 minutes per hour, which is sufficient to keep the pebbles wet.
Because the greenhouse is not systemically heated during winter, we selected native, easy to keep fish (carp and roach). So, when plant production comes to a stand-still, the fish also go into a "winter sleep" (hibernation).
The aquaponic system was constructed from:

• 10 liter Planters: recycled from shut-down marijuana plantations, left by the police
• Substrate: recycled rock-wool, expanded clay pebbles and lava rock (8-16 mm). Lava rock is cheaper than clay pebbles, but it can create basic water (high pH). We found that a 50/50% mix resulted in pH stable water.
• Rack: untreated wooden beams, with 2 metal L's as top support for the planters
• Pump: 200 Watt bilge pump
• Tubes: 20 mm PE tubing, with holes and little reeds sticking out for each of the top row planters.
• Aquarium and mix tank: Wooden boxes with pond liner
  

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