This diagram shows the detail of one of the growing beds. The level of the water is regulated by a contraption called an "auto-siphon". This device is made out of readily available materials and has no moving parts, thus reducing the amount of maintenance necessary to keep the system running properly. The height of the internal stand pipe of an auto-siphon determines the level that the bed will fill to and consequentially, the time that each flood cycle takes. Generally, this system takes about 20 minutes to fill and 5 to drain. These beds are also equipped with a small hole near the bottom of the stand pipe to slowly drain the beds during the night time when there is no sunlight to drive the system's pump. To have more control over the system and to allow it to adapt to variable climatic conditions (yes, sometimes there are cloudy/rainy days on Mfangano...) there are individual taps installed on each of the beds to allow slower or higher flow rates into the beds.

The basic principles of aquaponics show that you can grow both plants and fish at the same time in a closed loop system. The only inputs are energy from the sun and food from various sources. We tried to integrate as many naturally occurring (Free!) food sources as we could into the system to reduce, if not eliminate the need to buy commercial feed stocks. The inclusion of food scraps, water hyacinth (a disastrously invasive species for Lake Victoria), lake flies, and duckweed grown on site provides a varied and nutritious food stock for the omnivorous tilapia.

Inside of the growing medium (in this case smooth river stone gathered near the site) there are beneficial bacteria that change the ammonia produced by the fish waste into nutrients that the plants in the system can readily take up (Nitrites>Nitrates). These little guys are the key components of the system and without them, the whole thing would plummet into a state of chaos. They are naturally occurring in the air and in the water so therefore, as long as there is balance in the system, these bacteria will be present, working away. This cyclical movement of water from fish waste laden water to clean aerated water takes about 25 minutes per cycle and keeps the water clean. The fish feeding cycle is accommodating the unique circumstances that this system runs off of. The fish are only fed in the morning and early afternoon, leaving most of their waste to be produced and processed while the sun is still shining (therefore, when the pumps are still running...) In the evening, a set of DC powered aeration pumps keeps the water oxygenated and moving despite the incoming solar power.

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.

One week in....

After the long journey from Nairobi to Kisumu to Mbita to Mfangano, we have all of our materials and an exciting 4 weeks ahead of us. The EK Design Guild (Gaby, Sungu, Sam, and Mike), myself, and two design students from the US (Jonathan Dessi-Olive-UPenn Architecture Masters Candidate & Amanda Bednarz-UOregon Landscape Architecture Masters Candidate) got our feet filled with clay soil and shovels and went to town.
We made a ton of progress this week on the solar powered aquaponics set up on Mfangano Island.

Transit.
A crazy matatu trip from Kisumu to Lwanda Kotieno where we caught the ferry to Mbita for the night.

Strapping all of the materials to the top of the matatu at our favorite hardware store...

Day 1.
 -Dug the trench hole (8' x 37' x 3' deep)
-Moved the fishing boat into place
-Leveled Boat and backfilled with Kokato (crushed stone)
-Went on a piki-piki (small motorcycle) gang ride to find 3 old telephone poles to be used in the        project.
-Scored and Split the poles with circular saw, axe, and wedges.

Splitting the telephone poles into 4 pie shaped sections.

Day 2.
-Dug Post Holes
-Finished Splitting Poles
-Fastened Coo-coo mesh to boat interior
-Backfilled Trench to level boat


Day 3.
-Set up site grid
-Hauled Sand/Concrete/Kokato
-Set 1/4 of the posts/footings

Day 4
-Set 3/4 of posts/footings

Most of the posts split and footed deep into the soil.

Day 5
-Ferro cemented the interior of the boat with waterproof concrete/sisal fiber mixture

Everything is moving along very well. All day long, people are coming up to the fence directly beside the project site and asking questions, watching the construction, and everyone can feel the excitement around the project building up slowly. Fishermen are coming wondering when they can begin to buy bait fish. Farmers are coming wondering how big the po-po's (papayas) will be when they are grown like this. Boat builders are coming and remarking that the boats that are leaking and beyond repair are numerous and they want to know how to convert them into fish farms... A lot of research done in the last couple of years has provided incredibly useful but there is nothing that compares to learning from building the system, interacting with the people who will be using it, and adjusting the system accordingly.

More to come...

Made it to Nairobi after the most hellish plane trip that I have ever experienced... Delayed, rescheduled, waitlisted, rebooked, delayed, cancelled, rerouted, delayed, wtf KLM?? Here finally. So good to be back on Kenyan soil again...albeit three days late. I have to say that both United airlines and KLM will be receiving a heated letter from this guy.

Went to Kisumu to find the parts for the aquaponics system... virtually nothing that I had hoped would be available was there so some innovation was needed. I kind of expected that this would happen so was not too disappointed... New materials, new construction method, new design. Oh how I love iteration...

In Nairobi at the moment with good friend and US head of the Kibera Girls Soccer Academy helping them design their new school dormitory and support center. Had a crazy day yes walterdayking through the maze that is Kibera getting a lay of the land. No signs, only small little passages 3' wide between mud houses with tin roofs. Reggae blasting from the cantinas and cooking smoke rising in the sunshine. I'll upload some pictures soon... 

Ground was broken this morning on Mfangano, can't wait to see all of those shinin faces!

-Mookie