The completion of the aquaponics farm on Mfangano Island, Kenya was a huge success. Our team of US architecture students and Kenyan fundis (skilled workers) finished the project in time, within budget, and with no huge hick-ups in the process.

After many iterations as to the materiality, sizing, and operation of this system, our team created a system that utilized recycled materials from the surrounding area and cheap, readily available building materials with solar power to create a self-contained off-grid aquaponics system.

The system is comprised of four 6' W x 12' L x 1' H steel growing beds, stacked on on top of each other between two levels to accommodate different types of leafy greens and fruiting vegetables. The base of the system is an old fishing boat which was in disrepair and conveniently was providing some nesting space for catfish when we found it. The boat was sunk 3' below grade, stripped of its interior supports, ferro cemented, and sealed with poly. Hopefully this yellow poly will impart a nice yellow hue to the tilapia. Discarded telephone poles found on the side of the single ring road of Mfangano were purchased from the local power company, split into 4 pie shaped wedges at ~15' tall and sunken into the ground using concrete footings and ferro cement termite protection above grade.

The electricity for the system is supplied completely by a solar array. Two 245W panels provide pumping power when the sun is shining to a 4500L/Hr Dayliff well pump. This pump delivers water to all 4 beds at about 12 L/min and diverts a portion of the pumped water back to the fish tank to provide extra aeration.




A smaller, single panel of 90W delivers power to a set of 2 12V DC batteries that power two aeration pumps, a security light, and a electric push pump which is used to top up the tanks when needed (Kenyan sunshine can cause a considerable amount of water loss due to evaporation) and to fill the soil based farm's 3000L drip tank 3 times a day.

The plumbing of the system uses independently controlled taps for each part of the system to allow for fine tuning of the flow rates into each of the growing beds and the diverted aeration spray bars. Because the slight variance in the amount of sunshine affects the flow rate of the pump (with maximum power point tracking on the pump controller, the differences are minimal) the taps need to be slightly adjusted every week or two to ensure that the auto siphons fill and drain properly.

Joel planting beans in one of the upper beds.

Each growing bed is equipped with a stand pipe of 7.5" and a bell of 8.25". The growing medium is washed lake stone of somewhat varying size taken from the native tilapia's natural habitat along the shores of Mfangano. Hopefully the variance in size (minimum at .5" diam maximum at 2" diam) will not clog the system once sufficient fish waste has been produced but sorting of the stones to a consistent .75" diam or 1" diam would solve this problem.

 The top level of growing beds will house the larger, fruiting vegetables which need a lot of sunshine and a lattice structure to grow on. Tomatoes, passion fruit, beans, peppers, and other fruiting veggies will be grown in the upper level.

The bottom bed with kale planted.

 The lower level of growing beds will provide a lesser amount of sunshine and headroom for smaller leafy greens. Kale (sucuma wiki), Lemongrass, lettuces, cabbage, and other greens will be grown here.

A view to the inside of the tank

The fish tank will hold approximately 8000L of water and be able to comfortably accommodate 350+ market sized nile tilapia in 7-8 months.We have chosen to start with a relatively low fish stocking density to prevent overly nutrient rich water and potentially fatal fish conditions while the techniques of tilapia rearing and hydroponic farming are honed by local fish farmers and organic farmers. Because the chemistry of the water used in the system is so important, dissolved oxygen levels, ph, nitrate, nitrite, ammonia, temperature, general observations of the water quality, fish health, and plant health are recorded on a weekly basis in the first 8 months and then recorded on a bi-weekly basis after the first harvest season is complete to ensure that the users of the system are aware of the effects of weather, fish development, and plant types that are used in the system.

The left over parts of the bow, turned into a sign for the farm

Signing the "hood".

An amazing team of people worked together to make this a true community inspired and realized project.