The Aquaponic Farmer

A Complete Guide to Building and Operating a Commercial Aquaponic System

Adrian Southern, Whelm King

• Publisher: New Society Publishers
• Year: 2017
• ISBN:
  9781771422475
• Topic: Tecnología e ingeniería
• Subtopic: Pesca y acuicultura

Profitable cold-water fish and vegetable production. Join the aquaponic farming revolution!

Built around a proven 120' greenhouse system operable by one person, The Aquaponic Farmer is the game changer that distills vast experience and complete step-by-step guidance for starting and running a cold-water aquaponic farming business—raising fish and vegetables together commercially. Coverage includes:

• A primer on cold-water aquaponics
• Pros and cons of different systems
• Complete design and construction of a Deep Water Culture system
• Recommended and optional equipment and tools
• System management, standard operating procedures, and maintenance checklists
• Maximizing fish and veg production
• Strategies for successful sales and marketing of fish and plants.

As the only comprehensive commercial cold-water resource, The Aquaponic Farmer is essential for farmers contemplating the aquaponics market, aquaponic gardeners looking to go commercial, and anyone focused on high quality food production.

Aquaponic farming is the most promising innovation for a sustainable, profitable, localized food system. Until now, systems have largely focussed on warm-water fish such as tilapia. A lack of reliable information for raising fish and vegetables in the cool climates of North America and Europe has been a major stumbling block. The Aquaponic Farmer is the toolkit you need.

What Is Aquaponics?

A Primer on Aquaponics

THE WORD “AQUAPONICS” was coined in the 1970s as a combination of the words “aquaculture” and “hydroponics.” Aquaculture is the cultivation of aquatic animals and plants in natural or controlled environments. Hydroponics is the growing of plants without soil, using water to carry the nutrients. The term “aquaponics” was created to designate the raising of fish and plants in one interconnected soilless system.

Aquaponics can solve the major problems of both freshwater 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.

Fish farms in natural bodies of water, often called “open net pens,” are rife with problems, notably their potential for negatively impacting wild fish stocks. We do not support such farms, and they are not considered in this book.

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.

The aquaponic cycle.

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. We cover this topic in depth in Chapter 6.

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 1980s, 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 to develop, by around 1999 Dr. Rakocy’s system 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 have allowed us to modify the work of such visionaries as McMurtry and Rakocy to cold-water production, better suited to colder environments.

Aquaponic Ecomimicry

Ecomimicry is the design and production of structures and systems that are modelled on biological entities and processes. Aquaponic systems are manufactured environments that attempt to replicate a complex natural system. Every component and process in an aquaponic system has a natural counterpart.

Imagine a freshwater ecosystem. At a high elevation is a lake in which fish constantly produce waste in the form of ammonia and feces. A river flows from the lake carrying these wastes. Along the bottom of the river are layers of gravel and sand which are home to various bacteria and invertebrate detritivores (worms, insects, crayfish, etc.)

As waste-laden water flows down the river, feces sink to the bottom and are trapped in the gravel where it is eaten and broken down by detritivores and bacteria, converting it into elemental constituents and minerals. Ammonia (a toxic form of nitrogen) in the water is nitrified into nitrates. Without bacteria and detritivores, the waste would eventually build to toxic levels.

The river continues downstream to lower elevations and eventually meets a wide, flat wetland area. Here it slows and spreads out, depositing mineral-rich sediments where vegetation abounds.

After being filtered of its nutrients and sediments in the wetland, the water ends its downhill journey in the ocean. But this is not its end. Evaporation and evapotranspiration from plants combine to form clouds, and their moisture falls as rain, which collects in large bodies of water such as lakes, and the cycle repeats.

All these natural processes are found in an aquaponic system: the fish tanks are the counterpart to the lake, the filtration systems are the gravel in the river, and the hydroponic subsystem is the wetland. The main water pump serves as clouds by returning the water to the high point in the system: the tanks.

As we are mimicking a natural ecosystem, many challenges found in an aquaponic system are also found in nature. Nature had billions of years to evolve solutions which may be replicated in aquaponic farms by imitating nature.

Aquaponics, Permaculture and Sustainability

We believe aquaponics is a system of permaculture. All three tenets and twelve principles of permaculture design are realized within an aquaponic system, from conception and design to operation.

One of the core tenets of permaculture is the “return of surplus” which is maximizing the efficient use of resources and eliminating waste. Often, waste can be eliminated simply by recognizing it as a resource and using rather than discarding it. An aquaponic system has this tenet at its core, as observed in the relationship between fish, bacteria and plants.

Aquaponics has inputs and outputs. When permaculture design principles are applied, the inputs are minimized and used efficiently and the outputs are recycled back into the system as inputs. At Raincoast Aquaponics, we extract five different uses from every kilogram of fish feed and three uses from every liter of water.

The fish feed is used to raise fish (1), which in turn feed plants (2) via the bacteria. The resulting fish waste is captured and converted to a fertilizer product (3), and the crop residue (compost) is fed to pigs and converted into bacon (4). Pig waste is composted and used to build soil for growing field crops (5).

Water is first used to purge fish prior to harvest (1), and then used to top up the main system (2). The effluent flushed from the system is used to water field crops (3) after most of the fish waste has been extracted.

Aquaponic Plant Systems

There are several commonly used aquaponics systems whose names refer to the method of plant production. Systems of raising fish are all very similar, thus not considered in naming aquaponic systems. In all systems, two basic functions are found: water is cycled between the fish and the plants, and bacteria convert fish waste to beneficial minerals.

The four most commonly used aquaponic plant production systems are: Deep Water Culture, Drip Towers, Nutrient Film Technique and Media Bed.

Deep Water Culture (DWC): water flows down long troughs of water, typically about 12″ deep, like a slow-moving stream. Rafts, typically made from styrofoam, float on the water with a pattern of holes cut into them. Small open-bottom pots, called net pots or slit pots, fit into the holes. Plants are supported in the pots by a variety of different mediums. The roots of the plants are suspended and grow in the moving water.

DWC troughs with floating polystyrene rafts.

Drip Towers are tubes, typically made from PVC, with either holes or a slit running the length of the tube on one side, suspended vertically in rows. The towers contain a growing media into which plant roots grow. Water is continuously fed into the top of each tube and collected at the bottom to cycle through the system again.

Nutrient Film Technique (NFT) also uses tubes, typically PVC, with holes on one side. Whereas drip towers are suspended vertically, NFT tubes are mounted horizontally on a slight angle with the holes facing upwards. Plants are grown in small net pots inserted into the holes in the tubes. Water, continuously fed into the high side of the tubes, flows down in a thin film contacting the roots and is collected at the low side to cycle through the system again.

Healthy roots under a DWC raft.

Media Bed is a type of flood and drain production with numerous possible configurations. In all configurations, watertight growing areas are flooded at regular intervals by pumps then drain back to cycle through the system. The growing areas are filled with a pebble-lik...