Aquaponic setups are generally closed systems, by which water and nutrients are recycled between the aquatic animals and crops, with water added only as needed. However, other inputs are required, such as feed for the fish, as well as certain micro-nutrients (e.g. iron) that are often needed to keep the crops adequately nourished and to keep the pH of the water in balance. Microorganisms are also required by the system so that the ammonium produced by the fish can be reduced to a form of nitrogen that the plant roots can readily absorb (i.e. nitrate). This means that oxygen, pH, iron, ammonia, nitrite and nitrate levels need to be at acceptable levels to make the entire system non-toxic and productive.
Considering all, aquaponics systems are quite complicated and aren't as easy to set up and maintain as basic container gardens. Not just anyone can install such a elaborate system and/or operate it so that vegetables and fish are continually in production. Therefore, a certain degree of expertise and planning as well as the capacity to carry out long term management are required. The cost of installing such systems can also be expensive. However, aquaponics systems are quite appealing to many, and can be feasible, especially where production areas for vegetables are limited (as well as access to fresh water), and the demand for aquaponics products is high.
The key product of most aquaponic systems is vegetables. So in places where most vegetables are plentiful and cheap, aquaponic systems may have trouble paying for themselves.
With the assistance of our own aquaponics guru, Scott Breaden, we have been slowly setting up a small demo aquaponics system at the ECHO Asia office in Chiang Mai. After months of gradual installation of components, our system is still not even close to full production capacity. But we are learning lots of valuable lessons in the process.
However, I recently came across a very impressive and productive aquaponics system at Aloha House, an orphanage with a farm in Palawan, Philippines. There are actually two major aquaponics systems at Aloha House. A large, outdoor system has been set up on a sloping plot of land that is made up of several long, cement, watertight crop-production tanks through which the water flows by gravity from the top tank to the bottom fish tanks before being clarified and pumped back up to the top. In addition to tilapia, this system currently produces tomatoes, salvinia (Salvinia molesta - an invasive aquatic fern used at Aloha House to feed livestock and fish), rice and various vegetables such as watercress. Ducks are also incorporated, having regulated access to certain parts of the system so that they can feed on salvinia and snails and be happy.
A second roof-top system at Aloha House enables the level of the water pumped up from the tilapia tanks to rise and fall in a series of shallow, plastic-lined trays, allowing leafy vegetable crops (such as lettuce) planted in cups and situated in the trays to remain adequately watered, aerated and supplied with nutrients. Strategically placed biological filters that use rocks, soil and plants (such as nasturtium), as well as synthetic filters, help to reduce sediments and keep the water flowing. Water used for both systems at Aloha House is approximately 75 percent rainfed, with rain water efficiently harvested from roofs for use in the aquaponics system.
Keith Mikkelson, founder of Aloha House, stresses that his system took years of trial and error and considerable capital before becoming productive enough to produce both food and income for the orphanage. Although he has a lot of interested visitors, considering the cost, expertise, time and management required to make aquaponic systems practical, Keith admittedly talks most interested parties out of setting up their own.
For more information about the Aloha House aquaponics systems, contact Keith Mikkelson at firstname.lastname@example.org.