WHAT IS AQUAPONICS?
The word “aquaponics” is a combination of the words “aquaculture” and “hydroponics”. Aquaculture is the raising of fish. Hydroponics is the growing of plants without soil, which means growing plants in a medium that is inert. Aquaponics is the raising of fish and plants in one interconnected soilless system.
Aquaponics can solve the major problems of both aquaculture and hydroponics.
The major problem in land-based aquaculture is that fish waste in the water creates continuously elevating levels of ammonia. If left unchecked, this toxic element will rapidly kill the fish. The aquaculture industry typically uses one or both of two options to resolve this problem: a constant supply of fresh water to replace the toxic water and/or expensive filtration systems. Neither is ideal. The former not only uses voluminous quantities of our precious fresh water but also creates equally large quantities of high ammonia water that is toxic to any natural ecosystem. The latter is simply very expensive. The high cost is especially pertinent to smaller commercial operations as most filtration units only make financial sense at large economies of scale.
The major problem in hydroponics is the ongoing need for large inputs of fertilizers. A soilless production system means all the minerals - all the food - required by the plants must be continually added. Fertilizers are expensive and the vast majority are fossil-fuel derived, often referred to as “chemical” fertilizers. Available organic fertilizers are not commonly used because they are less water soluble thus more likely to cause problems and can be several times more expensive than their chemical counterparts. Hydroponic farms are often also a major water consumer as many use a drain-to-waste system. Even hydroponic farms that recirculate water must drain and replace their water regularly as they do not host a living ecosystem that balances itself.
By combining fish and plants into one system, aquaponics can solve the primary problems of both aquaculture and hydroponics. Fish waste provides a near perfect plant food and is some of the most prized fertilizer in the world. The plants, using the minerals created from the waste, do most of the work of cleaning the water for the fish.
The fish feed the plants. The plants clean the water. The symbiosis is as logical as it is effective.
The third living component in aquaponics is bacteria. The whole system hosts specific types of bacteria that serve two roles. One family detoxifies ammonia in the effluent by converting it into nitrates. Another family mineralizes organic material (primarily fish feces and uneaten feed) by breaking it down into its elemental constituents which are usable by plants. Without this vital conversion in a closed system, both fish and plants would rapidly die. Establishing the bacterial cultures and monitoring their health is one of most important tasks of an aquaponic farmer.
A VERY BRIEF HISTORY OF AQUAPONICS
Although modern aquaponics is only a few decades old, the concept of combining fish farming and plant production for mutual benefit is thousands of years old.
Since ancient times, fish have been raised in flooded rice paddies in China. The fish and rice are harvested at the same time annually and the technique is still used today. Ducks, sometimes in cages, were kept on the edges of fish ponds so their excrement could be used to feed the fish.
The Aztecs had advanced techniques of aquaponic farming called chinampas that involved creating islands and canals to raise both fish and plants in a system of sediments that never required manual watering, achieving up to seven harvests per year for certain plants.
In 1969, John and Nancy Todd and William McLarney founded the New Alchemy Institute in Cape Cod, Massachusetts, and created a small, self sufficient farm module within a dwelling (the “Ark”) to provide for the year round needs of a family of four using holistic methods to provide fish, vegetables and shelter.
In the mid 1980’s, a graduate student at North Carolina University, Mark McMurtry, and Professor Doug Sanders created the first known closed loop aquaponic system. They used the effluent from fish to water and feed tomatoes and cucumbers in sand grow beds via a trickle system. The sand also functioned as the biofilter of the system. The water percolated through the sand and recirculated back to the fish tanks. McMurtry and Sanders’ early research underpins much of the modern science of aquaponics.
The biggest leap came from Dr. James Rakocy at the University of the Virgin Islands. From around 1980 through 2010, he was Research Professor of Aquaculture and Director of the Agricultural Experiment Station where he directed voluminous research on tilapia in warm-water aquaponic systems. His research on the conservation and reuse of water and nutrient recycling remains the greatest body of modern work on aquaponics. Though it took many years, by around 1999 the system developed by Dr. Rakocy had proven itself to be reliable, robust and productive. His developments are used today from home to commercial scale aquaponics.
Our work has been primarily developing systems and protocols that allow us to modify the work of such visionaries as McMurtry and Rakocy to the cold-water production better suited to colder environments.