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.