Aquaponics

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[edit] INTRODUCTION

Background “Aquaculture is currently the fastest growing animal food production sector and will soon supply more than half of the world’s seafood for human consumption” [1]. It has been used in many different cultures, mainly for food production and removal of toxic wastes, like those produced by landfills [2]. Different types of bacteria and algae have been used to treat this wastewater (such as the algae Gracilaria birdiae) [3]. Aquaponics is an emerging part of aquaculture that uses the natural interaction between bacteria, fish and plants to transform waste into clean water.

What is Aquaponics? Aquaponics is a method of food production that integrates aquaculture with hydroponics. This symbiotic relationship facilitates a sustainable system with little input necessary. Good bacteria builds up, which then converts the toxins produced from fish waste into nutrients used by plants. By absorbing this nutrients, the plants filter the water, giving the fish a livable environment. This cycle helps keep the tank in good shape for both fish and plants.

Producing food with this method is about as organic as you can get. With this set up, there is no need for fertilizer because the fish waste is all that is necessary for the plants to grow. Herbicides also are not needed because there is no soil used to grow the plants, and could even be harmful to the fish. This system is especially great for areas with poor soil quality since it is not responsible for providing nutrients to the plants. You can grow large quantities of plants in small areas, without needing a large amount of land. Aquaponics is a great way to sustainably grow fresh fish and vegetables for a family, to feed a village, or generate a profit in a commercial farming volume. Not to mention the fact that you can produce your own dinner and side dish in one system. The best thing is that when your fish get big enough, you can eat them! [4]

History Aquaponics has recently resurged in popularity [5], however, this masterpiece of engineering and biology was first employed by ancient civilizations [6]. Polycultures were also created in China and Thailand where fish (as well as other species such as swamp eel and pond snail) were put into the rice paddies to aid in production of the plants and serve as another food source [7].

Where is Aquaponics used? Since the renewed excitement of aquaponics, countries around the world have started benefiting; these countries including the USA, those in South America, many parts of Asia, Australia and parts of Africa [8][9][10][11]. Even in the brackish water in the Negev desert there has been aquaponic systems set-up with adequate success of plant and fish growth [12]. Most operations fall under one of the following categories: research, educational, non-for-profit, commercial or private hobbyists[1]. Although most systems are small scale right now, the advancement in technology has led to a “steady increase in the number of commercial applications, two major areas of concern, namely profitability and waste management, have stimulated interest in aquaponics as a possible means of increasing profits while utilizing some of the waste products”[5]. A more detailed explanation of how the aquaponic system has been implemented in these different countries can be found in later sections.

[edit] COMPARISON OF METHODS

In order to fully understand aquaponics, it is imperative to understand that it uses both methods of aquaculture and hydroponics to grow its sustainable crops. By learning about the two methods you can fully appreciate the advantages and disadvantages of these three farming methods.

[edit] Aquaculture

Aquaculture is the farming of aquatic organisms such as fish and shellfish. This is a specialized form of growing where fish are raised in tanks, which are normally densely packed. Since there are such high quantities of fish together, the amount of waste accumulates at an enormous rate. In order to keep the ammonia levels down and prevent diseases, different forms of filtration need to be running constantly, requiring a high level of energy input.

[edit] Hydroponics

Hydroponics is a method of growing plants in a mineral water solution with no soil. This system allows for a more efficient growing method that is equipted with less space, less labor, and water. Since the plants are in ideal water conditions they don't need excises water, where normally much of the water is wasted. This type of system requires an input of nutrients.

Advantages Disadvantages
Organic Farming *Organic farming has become popularized in the marketplace because it is presumed to be a healthier way of growing food.
*Utilizes wastes for fertilizer.
*Uses natural pest control.
*Biological system produces better tasting and, sometimes, more nutritional crops.
*Uses more land than traditional farming.
*In most cases, it costs more to grow and certify organic crops than other methods of farming.
*USDA certification is losing value as agribusiness replaces small-farm organic production.
Inorganic Hydroponics (uses mined and manufactured fertilizers) *Produces a high volume of crops in a small space.
*Combining it with controlled environment agriculture results in consistent, year-'round production.
*Dependent on manufactured and mined fertilizers that are costly, rising in price and becoming harder to get due to increased demand worldwide.
Recirculating Aquaculture *Produces large volumes of fish in a small space. *Recirculating systems have a high rate of failure due to high stocking rates and low margin for error.
*Produces large waste stream.
Aquaponics (Organic Hydroponics) *Aquaponics has all of the advantages of organic farming, hydroponics, and aquaculture! Plus:
*Fish waste provides fertilizer for plants.
*Fish do not carry the pathogens, such as e-coli and salmonella, which warm-blooded animals do.
*High water volume in raft aquaponics reduces risks for fish production.
*Aquaponics demonstrates a natural cycle between fish and plants and is the most sustainable of the four methods presented here.
*With consistent bio-mass in the fish tanks, plants thrive.
*Management requires someone trained in raising both fish and plants.
*A major loss in the fish tanks can disrupt plant production.

Aquaponic Food Production: Raising Fish and Plants for Food and Profit, Rebecca L. Nelson with contributions from John S. Pade


[edit] DESIGN:Key Features and Components

One of the noticeable features of the aquaponic system is the immense number of different ways it can be constructed. Despite this diversity there are five key components in any aquaponics set-up: rearing tank, solids removal, bio filter, hydroponics subsystem, and a sump (Fig.1;[8]). These key components all accomplish the following functions, “finfish and plant production, removal of suspended solids, and bacterial nitrification [1].

Fig 1:Not to scale diagram of the different components important in an aquaponics system.


[edit] Rearing Tank: where the fish are grown

There are three different types of rearing techniques: sequential rearing, stock splitting and multiple rearing units [8]. Each of these different techniques has benefits, downfalls and requires different layouts. For example, sequential rearing requires many different age groups of fish in a single tank. This set-up is less complex than the other rearing techniques. However, it can induce stress in the fish that are not fully-grown for market when others are taken, it also makes it difficult to keep track of stock records and stunted fish avoid capture [8] . Another technique for rearing is called stock splitting. In stock splitting, the fish are split into two different tanks randomly when the first tank reaches carrying capacity. Although this technique helps avoid the carry over of stunted fish, the stress induced by transferring the fish can be detrimental to their overall growth[8] . The last common technique is a system with multiple rearing units. In this system, populations start at different ages and are transferred to larger tanks when the fish are big enough [8].

[edit] Solid Removal: removal of larger organic waste

The type of solid removal system depends on how much organic waste is produced in the system (aka. how many fish are being raised to how many plants are being grown) [8]. If there is more fish waste than can be maintained by the number of plants in the system, then a solid removal device such as a micro screen drum is necessary [8]. These intermediate filters help collect the solid and “facilitate conversion of ammonia and other waste products prior to deliver to hydroponic vegetables”[11]. This comes into play in the commercial scale systems and clarifiers have been used (Fig. 2). The clarifier system collects solids at the bottom of the cone. It does require fish to be in the tank to feed on waste that might be near the top and keep the pipes clean. Netting is also set up after the clarifier to catch excess organic waste that has escaped the clarifier. This netting needs to be cleaned once to twice a week. It is important to remove these nets because a build up of organic material can lead to anaerobic conditions that can kill the fish [8]. Certain water quality parameters are required to raise fish and plants including a consistent pH, dissolved oxygen concentration, carbon dioxide, ammonia, chlorine, nitrite and nitrate [11]. The sludge collected off of the nets can be used to fertilize other crops, or in urban settings, can be used in wastewater treatment plants to clean water [8]. On a smaller scale system waste removal may be unnecessary (where there are small amounts of fish relative to the plant growing area) [8]. In these systems, there is usually a direct flow of water from the fish-rearing tank to “gravel-cultured hydroponic vegetable beds” [11].

Fig 2:A) A clarifier works by water first entering the B) central baffle then it moves to leave either through C) the discharge baffle or into the D) outlet to filter tanks or out through the E) sludge drain.[8]

[edit] Biofiltration: utilizing bacteria

A vital part of the aquaponics system is the removal of ammonia that is excreted as a metabolic waste product from the gills of fish[8]. If there is too high of a concentration of ammonia then the fish will die [8]. This is prevented through the nitrification of ammonia. During this process ammonia is oxidized to nitrite and then to nitrate. Aquaponics takes advantage of these naturally occurring nitrifying bacteria, Nitrosomonas and Nitrobacter, which mediate this process [8].

Fig 3:A diagram of the natural cycle that nitrogen undergoes in nature. The diagram specifically shows the point where nitrifying bacteria, Nitrosomonas and Nitrobacter, are key players in converting toxic nitrite to relatively non-toxic nitrate.[13]

These naturally occurring nitrifying bacteria like to grow in biofilms along different surfaces. To maximize the bacterial growth biofilters in aquaponics are, most commonly, constructed from sand, perlite, or gravel [8][11].

Fig 4:A simple diagram of the set-up of an aquaponics system[14]

[edit] Hydroponics system: where the plants are grown

These different biofilters are also important to recognize when drawing distinctions between different types of hydroponics systems. In smaller set-ups, gravel is used because of its calcium benefit to the plants [8]. This type of system needs constant ebb and flow of water. The downfalls of this system include clogging from left over roots, microbial growth and a lack of complete water circulation (lack of flow leads to anaerobic zones and poor plant production)[8].The lack of flow could also lead to poor water quality and fish death [11]. If the aquaponics system is bigger and constant water flow is not an option, a sand system is a good choice [8]. Larger granules of sand are recommended to prevent clogging of the tubes. If neither sand nor gravel are an option, perlite is another wonderful choice [8]. Perlite based systems are good if small rooted plants are being grown and the grower is willing to remove all the solids before it enters the hydroponics portion. If this is not done, anaerobic portions will form [8].

[edit] Sump: collection of clean water

The sump is the one place where water is pumped in the system. This is a good place to add water if the system has lost any. [8]

[edit] SCIENTIFIC THEORY: how does an aquaponics system work

Aquaponics is a circulating system that takes advantage of natural biological processes. Below, each part of the system (plants, fish, water and bacteria) are explained:

[edit] Plants: what do they need and how do they grow best?

Firstly, it is important to address the plants that are best adapted to the aquaponics system. This system best supports plants that have low nutrient requirements like watercress, basil, chives, spinach, herbs and lettuce [11]. However, tomatoes and cucumbers have also been grown [15]. If anaerobic conditions are created because of poor water flow, then these zones could also lead to lack of plant growth [8].

An example of tomato plants in a media-filled system. Personal photograph by author.

[edit] Root Crops

Despite growing in a rocky medium, such as clay pebbles or gravel, root crops are said to do reasonably well in an aquaponics system. A short list of plants that could be grown with aquaponics would consist of lettuce, chives, watercress, basil, cabbage, tomatoes, squash, and melons. Early on in the development of aquaponics, it was thought that only leafy crops could be grown. Now, over 60 different types of food have been grown successfully, as tried by the Crop Diversification Center in Alberta, Canada. [16]

[edit] Invasive Roots

It is not advisable to plant a species with fast growing roots, such as mint. An aggressive root system will grow into the piping and overtake the system. [4]

[edit] The Media-Filled System

Because media-filled systems are most common for at-home food production, this section will be elaborated upon, as it pertains to the media-filled method. Many components of this method are also used in raft and NFT systems. The basic pieces of a media-filled operation are the grow beds, the fish tanks and a clarifier. Of course, individual pumps, aeration mechanisms, water heater/chiller, back up power systems and a variety of plumbing using PVC piping are also needed.

[edit] Growing Medium

A standard 1/4 inch (0.66cm) gravel, perlite, or hydroton, a type of clay pebble commonly used in hydroponics, can be used as growing mediums. Gravel is slightly less expensive, but the hydroton allows for easier planting in some cases because of its uniformity.

[edit] Volume

One fish needs about 10 liters, or 2.5 gallons of space to itself. So, if you have a 50 gallon fish tank, you can have 20 fish. The more water you have, though, will help to stabilize the system. The minimum recommended tank size is 250 gallons, or 1000 liters. The grow bed volume should be the same as the fish tank volume. [4] Smaller systems have been made with varying degrees of success.

[edit] Flush/Fill System

When using a grow bed, the media must be periodically flooded and drained. There are several methods by which this can be accomplished.

A proper flow is crucial for the delivery of oxygen to the roots and bacteria colony. [4] There are several methods by which to move water from the grow beds back to the fish tank. These include a bell syphon, a spill over, a toilet valve, or just a pump set on a timer. Any number of ways can be used to deliver proper amounts of water, nutrients and oxygen to the water in a Media-Filled System. The key is have a flow rate that will cycle the water through the system and not allow toxic levels of ammonia and nitrites to accumulate.

[edit] Plant nutrients

Depending on your system, it may be necessary to add certain nutrients to the water. Iron, calcium, magnesium, potassium and boron. These can be added in chelated form to the water every three weeks or so. Supplementing aquaponics with vermiculture, as described above, may circumvent this need.

Friendly Aquaponics have made a guide to identifying plant nutrient deficiencies

[edit] Fish: requirements for best fish production

Certain fish are better because they are more tolerant to changes. Tilapia is the most commonly used fish in the system [11][8]. Fish that have been included in the system include “tilapia, trout, perch, Arctic char, and bass…tilapia is tolerant to fluctuating water conditions such as pH, temperature oxygen, and dissolved solids” [11]. These different conditions mentioned before (ammonia, nitrite, nitrate, pH, dissolved oxygen, carbon dioxide) are important to monitor to ensure the highest growth rate of fish [11]. These conditions can be measured directly or indirectly through the “stocking density of fish, growth rate of fish, feeding rate and volume” [11].

[edit] Fish as Food

Depending on the climate you live in, it is best to use fish which are native to your area. This allows for the least amount of energy to be put into heating or cooling the fish tanks. It is also recommended to choose a hardy breed of fish that can survive fluctuations in water quality or temperature. Keep in mind that some fish eat their companions when they become larger and must be sorted out into separate tanks. [4]

[edit] Feeding

Fish food is the primary input into an aquaponic system, so choice of food is crucial for sustainability. [16]

There are several options for providing food for your fish. Most systems could advantageously combine several of these -

  • Pellet fish food. Feeding your fish can be done with a high-quality pellet food made of fish and soy. This is the most common and well-tested way of feeding fish in aquaponic systems, but it has the disadvantage of requiring a constant external input, which adds considerably to the running cost of the system. The following options can be used to bring the system to a closer approximation of a fully closed-loop system
  • Algae. Algae will grow endemically in almost any body of still water, and provide some food for the fish. Putting a plastic mesh (like an empty fruit crate) in your fish-tank provides a surface for the algae to grow on. Unfortunately, even in the best circumstances, it is difficult to fully meet the food needs of the fish with algae alone.
  • Fish food can be produced in the grow beds, if the chosen breed of fish will eat leafy greens.
  • Duckweed is also an excellent choice as it can be grown on the surface of an auxiliary tank, then harvested and frozen as needed. [4] Duckweed grows rapidly, has high protein and nutrient content for the fish, and there is a species of it to suit most climates. Also, duckweed absorbs ammonia, a byproduct of the fish, providing a protein-rich food that can be fed to certain types of fish. [17]
  • Worms. Some people practise vermiculture alongside aquaponics. This allows the inedible parts of the crops (or other organic waste you have around, like grass cuttings or whatever) to be fed to worms. The worms can then be fed to the fish. The compost produced in the wormery can be used to grow plants outside the aquaponic system, or can be used to make compost tea which can be added to the hydroponic element of the system. This diversifies the nutrients the plants receive, particularly supplying boron that may otherwise be lacking.

[edit] Nursery

Although fingerlings can be purchased, they need not be the only source to populate the fish tanks. To continue with the idea of a closed-loop system, a nursery tank can be set up and mating facilitated so that the fish population will sustain itself. It is important to move the young to a separate tank in some cases because the adults will eat them. [4]

[edit] WATER

In an aquaponics system, water quality is directly correlated with plant quality. Plants need certain minerals to thrive, and these minerals are provided by the fish waste. In a non-hydroponic growing situation, the minerals come from soil. In a closed hydro system, such as aquaponics, the minerals which enter the system are highly regulated. When growing plants in soil, you risk the plants taking up toxic minerals, [18]and subsequently consuming those in your end product. Therefore, aquaponics is a more pure form of organic farming, providing a higher level of regulation, resulting in a higher-quality product.

[edit] Clarifiers, Mineralization, De-gassing, and Biofiltration

The middle barrel in this system, which has been buried in the ground, acts as the clarifier. The grow beds are raised behind it, and the fish tank is buried in the front. Personal photograph by author.

The maintenance of water quality is critical for all parts of the system. One particularly important factor is this is the pH balance, because different parts of the system thrive in a certain pH. Therefore, some compromises must be made. Fish generally like a pH of 7.5-8, while plants do best at 6.0-6.5, and the bacteria colony works most efficiently at 7.0-8.0. The consensus for an overall pH is 7.0 for the system to function at its best. [16]

Reaching acceptable water quality levels requires different components depending on what type of aquaponic set-up is installed. There are three main types: raft, Nutrient Film Technique (NFT), and media filled beds. Raft systems, also called float, deep channel, and deep flow, grow the plants in floating styrofoam boards in a tank separate from the fish tank. NFT grows plants in long, narrow channels with a thin film of water flowing through them to bring nutrients to the plants' roots. Media filled beds are simply containers filled with a growing medium, like gravel, perlite, or hydroton, in which the plants roots are held, then they go through a flood and drain sequence to bring nutrients to the roots. [16] The first two methods are more common in commercial-size operations, while the last method is most commonly used in backyard operations, producing food on a small scale to feed about one family.

A clarifier is used to remove solids from the water column. This can be done in multiple ways. Conical clarifiers and settling basins facilitate the solids settling out of the water column; they are based on the concept of high specific gravity, compared to the water they are in.[16] Basically, this means they sink and can be captured at the bottom of a clarifying instrument, whether it be a settling basin or a conical clarifier. Another way to remove the solids is a micro screen drum filter that removes organic matter in a backwashing process. Removing solids is only necessary in the raft and NFT systems because in a media-filled bed, the solids are caught in the media, where they can then biodegrade without interfering in the function of any other system components. [16] Occasionally, having a clarifier in a media-filled system is helpful when lots of solid waste is present.

Now, you might be wondering how the system functions if the solids, which are essentially the fertilizer of the system, are removed. Before the clarifier, raft and NFT systems need a mineralization tank that is filled with some type of porous media. In this area, heterotrophic bacteria convert the waste into elements that are readily used by the plants. This process also creates gases such as hydrogen sulfied, methane, and nitrogen. Therefore, a degassing tank is needed to help release these into the air. [16] Again, this is not needed in a media-filled bed because the solids remain in the system trapped in the media.

Biofiltration provides a place for the bacteria colony to live. It is not necessary in raft and media-filled systems because there is enough surface area for the bacteria to colonize to a healthy level. However, in a NFT system, extra colonization space must be provided for a healthy colony to stabilize. This extension is called a biofilter. [16]

[edit] Aeration

Proper aeration of the water is vital for quality of fish life. Without enough oxygen, fish can die within 45 minutes. [4] Even if death is not immediate, gill damage can be permanent and slowly, the fish population will fall. This point is exactly why having a backup power system is important. Water aerators can be bought at an aquarium supply store but must be powered by electricity. So, if there is an electrical failure, oxygen will stop being supplied to the water and damage to the fish population will result.

An aquarium-type aerator is not the only way to add oxygen to the fish tank. In a media-filled system, the water flowing out of the grow beds can be arranged so that it falls from enough of a height to splash back into the fish tank, mixing air into the water. Again, if there were a power failure, the pump causing the aeration would also fail; no matter what measures are taken to provide adequate oxygen, an electrical backup is needed.

[edit] Bacteria: how do these bacteria help?

A vital part of the aquaponics system is the removal of ammonia that is excreted as a metabolic waste product from the gills of fish [8]. If there is a too high of a concentration of ammonia then the fish will die [8]. This is prevented through the nitrification of ammonia. During this process ammonia is oxidized to nitrite and then to nitrate. Aquaponics takes advantage of these naturally occurring nitrifying bacteria, Nitrosomonas and Nitrobacter, which mediate this process [8]). Bacteria from the roots of different types of aquaponics plants have been isolated in order to determine the strains of bacteria present and their function in the system [19][11][20][8]. In a type of waterwater treatment rhizoplane of the the reed family, Phragmites communis, a taxonomic study was done that determined a strain of Nitrosomonascommunis and Nitrosomas europaea (both ammonium oxidizing bacterium) were present on the roots [19].

Fig 5:Not to scale schematic of a UVI aquaponic system.[5]


[edit] Bacteria Colony

The bacteria colony that inhabits the entire system is responsible for the conversion of nitrites and ammonia to nitrates, which can then be used by the plants. Without this conversion, the nitrites, and to an extent the ammonia, would reach toxic levels and kill the fish and plants.[16]

[edit] Building up the Natural Colony

These bacteria are naturally found in the air and water, they need not be added to the system. A buildup of the natural colony can take 20-30 days, [16], sometimes up to 8 weeks.[4] Eventually, as with all natural systems, the components will fall into balance and remain stable with little upkeep.

[edit] Starting Your Own

However, to expedite the colonization process, a urea fertilizer can be added in very small amounts as a source of ammonia. [4]

[edit] No or low Power Aquaponic Systems

If wanting to construct a system with little or no power requirements (like if promoting aquaponics in a developing country) then a “Flood Valve” could be used [21]. This system works with only a pump that pumps water from the fish tank to the “Flood Valve… [and] it will work with flow rates lower than 100 gallons per hour” [21]. A specific design for this system is not yet out but it operates in a similar way to a “standard toilet valve” [21].

Other designs do not have valves but, instead, commit to manual labor. An aquaponics system was constructed for free in Thailand and requires no electrical input [22]. The following items are needed: a tank to hold the fish (like a large plastic tub), container for the plants, means to elevate plants above fish tank and a watering device [22]. To start up this system, it is important to put the fish in a least a week before. Also, before watering the plants, swirl the fish-rearing tank then fill the watering can. In this system, the fish-rearing tank will need to be cleaned periodically. Finally, it is important to flood containers at least three times a day [22].

[edit] OPERATION AND MAINTENANCE

Operation and maintenance will vary between all the different designs. In general, the different levels of nutrients and pH must be monitored [23]. It is also important to clear any “sludge” build up in the pipes between the different components of the system [24]. In the other sections where different systems were mentioned, there is more detail on techniques for maintenance.

[edit] EVALUATION OF SYSTEM

Many places in the world do not have easy access to greens or fresh fish [22]. Some of these places are located in our own backyard, in parts of urban centers that do not have grocery stores nearby. The evaluation of the aquaponic system has to take into account the importance that these, maybe scarce resources (fresh fish and greens), might provide to a community [25]. Talipia contains fat, protein and iron which are all important parts in a human’s diet [26].

If trying to evaluate the systems economic benefit, “to date, few studies have evaluated the profitability of small—and large—scale operations” [1]. It still is not clear if food safety would be a concern since there is a “risk of cross contamination, including spread of Samonella and Escherichia coli when fish and other animals are near produce”[1]. However, it is known that profits increase because of the following: 1) plant nutrients are produced for “free” by the fish 2) large biofilter’s are often unnecessary 3) water requirements are decreased 4) overall costs to run the system and for the infrastructure are shared by both systems [27].

Another way to evaluate the system is to analyze the efficiency of nutrient removal by the plants. This has been done by many scientists. In one such experiment, scientists tested the nitrogen excretion and uptake in the aquaponic systems by looking at growth performance, lettuce yields and nutrient retention [28]. In another experiment, the aquaponic system was set-up to analyze the removal of nitrogen by tomatoes and cucumbers. It was found that the highest removal was by tomatoes and the overall system had “69% of the nitrogen removal by the overall system could thus be converted into edible fruits”[29]. The yields of certain crops can also be used to evaluate the productivity of the system. In Graber et al. they analyzed four different tomato crops and found their yields to be higher in aquaponic when compared to hydroponic systems (Fig. 6).

Fig 6:The yield of different species of tomato crops grown in two different systems; aquaponics or hydroponics.[30]

To get the largest economic benefit through the most nutrient uptake, one study found that “the greatest plant growth was observed in the recirculating tank system where fish feeding rate, and subsequent dissolved nutrients, was higher. In that system, cord grass -Spartina biomass production was 25% greater than in constructed marshes and nitrogen uptake was twice that of natural marshes. Preliminary economic analysis showed that the plant production can generate supplementary income as the plants have relatively high value” [24].

[edit] IMPACTS

Different organizations around the world have set up aquaponic systems in parts of the developing world to provide fresh plants and fish to underrepresented communities. One such organization, The International Rescue Committee, constructed an aquaponic system with two 700-gallon fish-rearing tanks stocked with tilapia and used the wastewater produced to grow fresh plants[31].

In urban communities, aquaponics has been used to provide cheap fresh produce to individuals who cannot easily access it and in some cases, individuals have made profits off of urban aquaponic systems [32]. Currently, the University of Amherst Massachusetts is working on an aquaponics project in Uganda which will provide high-quality protein for the residents of the community[33]. See video at https://www.cns.umass.edu/about/news/2012/danylchuk-holingsworth-develop-aquaponics-for-developing-countries. Massachusetts Institute of Technology is also working on a project in Viet Nam that is providing tilapia and rice to a local province called Hoa Binh [34].

[edit] DISSEMINATION

Facts and information about aquaponics can be found all over the internet (such as here: http://theaquaponicsource.com/learn-about-aquaponics/) where an individual can learn about the science behind the system, how to set-up your own aquaponics system and talk (through blogs) to other individuals that have already experimented with their own aquaponics set-up. Since the renewed excitement of aquaponics, countries around the world have started benefiting from the aquaponics system. In the USA, North Carolina State University and the University of the Virgin Islands have been big players in advancing the technology [8]. Countries in South America, many of which suffer from extreme lack of water, are prime candidates for this integrated aquaculture and horticulture system because of its efficient water usage (Bishop, 2009). Japan, Taiwan, Bangladesh as well as many other countries in Asia have taken to aquaponics because of the possibilities of cheaply producing organic food in a condensed space. In Australia, scientists have been experimenting with different species of fish to farm because of the ban on Tilapia (the most commonly used fish in the system) [11]. Easily maintained, cheap and efficient aquaponic set-ups have been constructed in Africa [21]. Aquaponics is present in almost every continent on the globe [11][22][21][8] [35]. Most operations fall under one of the following categories: research, educational, non-for-profit, commercial or private hobbyists (most systems are small scale) [1].

[edit] Challenges with Dissemination

One of the main constraints with this system is that it can have quite large start up costs, requires a large amount of land for commercial scale systems and there is generally a “lack of large-scale models and trained personnel” [1].


[edit] Re-design

The amount of nutrients provided by the fish cannot be converted quickly enough in some cases by the nitrifying bacteria from nitrate to nitrogen that can be used by plants (Tyson et al., 2007). It is known that pH changes the nitrification rate, but the balance between the pH “good” for the bacteria, fish and plants is difficult in the current system, meaning that each has a different ideal pH[36]. [37]

[edit] HOME BUILT SYSTEMS

There are many ways someone can build an aquaponics system at home. It can be a fun and rewarding project especially if it is used to teach children about the life sciences. Investing in a home built system for food production purposes is a different thing entirely. There are many things that can go wrong in an aquaponic system because there are so many variables to the system. Water quality is the number one concern in aquaponics, and it can suffer major changes if just one piece of the system is out of balance or malfunctioning. So it is important with this investment, like any other, to understand what the risks are before you begin a project. Outlined below are a few things to look out for and ways to help design an efficient system. But this, like any document, is incomplete. If you do decide to build your own system you will no doubt encounter new problems. Do not be discouraged though, solutions are out there and if you keep reading and keep working the answers to affordable food production are out there.

In order to put together an aquaponics system you will need a few items. A kit can be purchased from organizations such as www.backyardaquaponics.com.[38] The system can also be built using your own materials. The basic components are a fish tank or an old bath tub, a submersible pump, PVC pipe to move the water from the pump to the bacteria chamber, an air pump and air stones. [39] Small scale systems make great classroom projects, as well. Students can learn problem solving skills involved with the technologies in play. [40] Other educational aspects include natural cycles, nitrification, biology, fish anatomy, nutrition, agriculture, math, and business. Schools throughout the United States and other countries are using aquaponics for grade school to college level educational experiences. [16]


[edit] Barrelponics

The Barrelponics Manual. Barrelponics is aquaponics in a barrel. Small, but scalable. If you would like a complete description of how to build a barrelponics system,pdf[1] offered by Hughey.[41]

This is an example of a system at Sierra Nevada College. Enjoy!

[edit] Farm fountain

Farm Fountain combines aquaponics and sculpture. It applies aquaponics as a vertical farming method to save space. How to build your own

[edit] FINAL TIPS

When designing a new system it is important to understand that water quality is going to literally be the life blood of the system. Without the proper flow rate and water conveyance, the system will function poorly if at all. In his instruction video Aquaponics Made Easy, Murry Hallam points out that in small aquaponics systems it is best to not have a system smaller that 1000L (265 gallons). This is because below that the amount of water in the system is less stable, with less water to act as a buffer when temperatures vary, or when there is a spike in fish waste.

Moving that amount of water around can use up a lot of energy as well and so in designing a home built system, focus on ways to use gravity to promote water transfer form one part of the system to the other. A good way to do this in the planning phase is to draw diagrams that show just where the water level will be in each tank. This way you know where in the system to order things and at the end of the diagram how much vertical lift you will need to achieve in order to move water though the system.

[edit] References

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[edit] Further reading