Can You Feed Your Family With Aquaponics?

Login or register to post comments Last Post 60554 reads   57 posts
Viewing 10 posts - 1 through 10 (of 57 total)
  • Fri, Jul 30, 2010 - 12:55am

    #1

    JAG

    Status Silver Member (Offline)

    Joined: Oct 26 2008

    Posts: 240

    count placeholder

    Can You Feed Your Family With Aquaponics?

Can Aquaponics Feed Your Family?

Over the last few years, I have done some research, and tinkering, in the field of aquaponics, as I find the ecological efficiencies inherit in its design most fascinating. For those of you who might be new to this subject, aquaponics is the synthesis of aquaculture, the growing of fish and other aquatic “livestock”, with hydroponics, the growing of plants in a soilless medium. Proponents of this field claim that one could feed a family quite easily with a moderately sized “backyard” aquaponic system, with the only inputs to an established system being fish food, electricity, seeds or transplants, and a few organic plant supplements such as liquid seaweed extract and chelated iron. 

Obviously the ability to provide high quality protein, omega 3 FA, and copious amount of organic vegetables for a family in such a small space is intriguing to those of us who believe the future will be very different from the present. It is the intention of this post to detail such a system and clarify its particular design and situational advantages / disadvantages so that we can answer the question “Can aquaponics feed your family?”. 

 

How An Aquaponic System Works

A basic aquaponic system has three primary components. Each component consists of an organism and its specific habitat. Water serves as the medium in which all of the components are mechanically and ecologically linked together. The three basic components are:

  • The first component is the fish and the fish tank or pond. 
  • The second component is the bacteria colony and its bio-filter media habitat.
  • The third component is the plants and the grow beds.

The system works in the same manner as a typical permaculture system, in which manure from livestock is composted and used as a nutrient source for food crops. Except that in an aquaponic system, the livestock are fish and the fish effluent (manure) is composted and delivered to the food crops via a water pump instead of by human facilitation. But the symbiosis of the system lies in the fact that as the bacteria and plants digest and assimilate the fish effluent, they also clean the water for the fish. So the three components of the system work together to form a primitive ecosystem.


The Nitrogen Cycle

As mentioned previously, the “composting” of fish effluent is performed by colonies of anerobic and aerobic bacteria. The ammonia that the fish excrete is converted by the bacteria in a two step process, first to nitrite, and then to nitrate. Each step in this conversion requires oxygen.


Ammonia and nitrite are very toxic to fish, while nitrate, the end product of bacterial processing is significantly less toxic to fish. Additionally, nitrate is an excellent fertilizer for plants and is rapidly removed from the water by the plants. In a natural environment, the nitrogen cycle is completed when the fish digest the plants. In an aquaponic system, the nitrogen is introduced in the form of fish food, and is removed from the system by the harvesting of the plants. 

 

The Fish

Aquaponic systems require a type of fish that can tolerate a high-density population. Some systems even recommend a fish density of 1lb of fish per 2.5 gallons of water to maximize the fertilizer concentration of the water for the plants. The major drawback to such a high density of fish is that a failure of the mechanical aeration system would result in the death of the fish population (from lack of oxygen) in under an hour. 

In addition to crowding tolerance, other factors in the fish selection process include a preference for non-predatory fish, fish that will readily eat vegetation and insects in addition to fish food, and the “plate-appeal” or nutritional quality of the harvested fish. Some examples of the fish types typically cultivated include:

  • Talapia (the most common in the US)
  • Largemouth Bass
  • Blue Gill
  • Catfish
  • Jade Pearch, Silver Pearch, Murray Cod, Barramundi (Australia)
  • Koi (as an ornamental fish, that can be eaten in a crisis)  

The Bacteria

The major considerations in regard to the bacteria are habitat, oxygen, and the seeding of the initial population. The first two considerations, habitat and oxygen, can be accomplished with the use of media beds (typically gravel of a uniform size) that is continuously flooded and drained with pond or tank water. An ingenuous mechanical method of creating this flood and drain action is with the use of a bell siphon.

The gravel in the media bed provides a tremendous amount of surface area for the bacteria to colonize, and the continuous flooding and draining of the bed provides more than adequate oxygen to fuel the nitrogen cycle. The flood & drain media bed simulates the bacteria’s natural stream bed habitat quite effectively.

Initially establishing the bacterial colony can take up to 2 months, and can occur naturally or be seeded. The tricky part is to establish the bacteria before you add the fish (fingerlings) to the system. This can be accomplished by running the system, and adding small amounts of urea fertilizer to the water in a progressive step-by-step manner, to substitute for the fish effluent. In this way a bacterial colony can be established to process the fish waste prior to the introduction of the fish.

 

The Plants

The plants are grown in the bacteria’s (soilless) media beds. Because of the constant supply of water, oxygen, and nutrients, the plant’s roots can achieve optimal uptake of each element from a significantly smaller root mass. This allows for a much denser plant spacing than what is achievable with soil cultivation. It also provides for higher plant growth rates than conventional gardening/agriculture. 

The media beds that the plants are grown in are typically one foot deep and 3 feet wide (and vary in length), and are elevated to waist level. The elevation of the beds provides for a gravity-powered return of the water back to the pond/tank, ease of access for the gardener, and some protection from insects. 

Just about any type of vegetable can be grown in these beds except for root crops (though there does seem to be some initial success with carrots in these systems). Even plants that “don’t like their feet wet” like citrus, do remarkably well in this system due to the superior oxygen delivery to the root system in a flood & drain media bed.

The plants do require some nutrient supplementation, as some nutrients introduced to the system in the fish food are retained by the fish and therefore not available to the plants. For example, chelated iron is often added to the media beds for consumption by the plants. Calcium carbonate is added (often in the form of crushed egg shells) both as a nutrient source for the plants and as a means of controlling the water’s pH balance. Typically a seaweed extract is delivered to the plants in a foliar spray and added to the water in the media beds. 

Aquaponic systems require an organic approach to gardening, as chemical insecticides and fertilizers will harm the fish and bacterial populations. The inverse is also true, as applying chemical or salt treatments to control fish diseases will adversely affect the plant and/or bacteria populations in the ecosystem. Many aquaponic gardeners use natural-extract foliar sprays and companion planting strategies to control plant pests quite effectively. Composting worms thrive in the media beds and help to keep the beds clean of accumulations of fish waste that build up over time (and also provide some vermicompost for the plants).

 

The Equipment

It should be noted that the aquaponic system described in this post is only one type. Some aquaponic systems use floating rafts with holes cut in them for planting sites. Other systems use what is called Nutrient Film Technique, in which the plants are grown in shallow channels and the nutrient solution (fish water) is streamed down the channel. Each system has its advantages and disadvantages, but the simplicity of the flood & drain media bed system is the most suited for home food production.

There are also better choices for media than just gravel. The best media seems to be hydroton, a lightweight expanded clay pebble with good capillary action, a neutral pH, and great surface area for bacterial colonization. Perlite and sand are also sometimes used as media.

The water pump is the power source for the entire aquaponic ecosystem, as without its continual operation the fish can die in a few hours, the bacteria colony experiences population deflation in as little as 4 hours, and the plants will experience water shock in a day or less. For this reason some systems design in redundancy by using two or more pumps in the system. It is possible to use 12V DC pumps that are powered by photovoltaics and a battery array, but expect the cost of the PV power system to be more than the aquaponic system itself.

In regard to maintaining adequate dissolved oxygen levels for the fish, bacteria, and plants, some systems employ air pumps and air stones to supplement the oxygen levels in the fish tank and/or media beds. Some systems also use a venturi nozzle on the water input to the media/grow beds to enhance aeration of the water for the bacteria and plant roots. A smooth sheet-type waterfall for the water returning (via gravity) to the fish tank also provides excellent aeration for the water in the fish tank/pond. 

Finally, a means of controlling the environment/climate of the aquaponic system can significantly enhance its productivity and ease of operation. For starters, the fish pond needs to be significantly shaded in order to control algae growth (and high water temperature), yet the plants will need all the sunlight they can get. Additionally, rainwater should not be allowed to flow into the system naturally (as rain), as it will dilute the nutrient concentrations in the system’s water (good for the fish, bad for the plants). And water temperature and air temperature need to be regulated in the winter to maximize production, because the fish eat less in cold water. All these factors can be addressed with a greenhouse/shadehouse enclosure for the system, depending on your climate, though many systems in operation today are outdoor installations. 

 

Can We All Get Along?

Despite the efficient design and operation, the learning curve for the aquaponic grower can be steep. Not only do you need to know how to grow fish and plants, you also need to understand the many interdependent relationships between all the ecosystem’s components. A “happy medium” in parameters such as water temperature, dissolved oxygen, and pH must be established and maintained in order for all the organisms to thrive. Also, the plant and fish crops must be seeded and harvested in a successive manner to maintain a balance in the nutritive and waste loads in the system. 

 

Can Aquaponics Feed Your Family?

  I think the answer to that is a qualified yes. These systems do provide a great deal of food in both private and commercial operations today. But like everything else, your only going to get out of it what you put into it. 

 

The Fourth Component: The Human

What I personally find so inspiring about aquaponics is that it elevates the role of a human being from an egocentric actor in his/her environment, to a designer, builder, and steward of ecosystems. I have to believe that within this new role, a role pioneered by the permaculture movement, lies the seed to a future of true prosperity for not just mankind, but all of nature. 

 

More Information

Despite the length of this post, I assure you that I only touched the surface of this subject. Below are some links to some more information and some available youtube videos on the subject.

 

Thanks for reading….Jeff






  • Fri, Jul 30, 2010 - 01:17am

    #2
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Re: Can You Feed Your Family With Aquaponics?

Alright, are you reading my mind while also being gracious enough to answer my questions?!   This is exactly what I’ve been wondering about the past few days!  

The previous owner of my property built 4 small interconnected pools.  They are unfortunately too far from the house and I have little use for them from a swimming/bathing perspective, but I’ve been wondering about how to use them for harvesting fish.  Harvesting plants with them hadn’t occurred to me until now, but could very well be feasible.  

Thanks – I’ve got a lot of studying to do!

  • Fri, Jul 30, 2010 - 01:31am

    #3
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Re: Can You Feed Your Family With Aquaponics?

[quote=Farmer Brown]

Alright, are you reading my mind while also being gracious enough to answer my questions?!   This is exactly what I’ve been wondering about the past few days!  

The previous owner of my property built 4 small interconnected pools.  They are unfortunately too far from the house and I have little use for them from a swimming/bathing perspective, but I’ve been wondering about how to use them for harvesting fish.  Harvesting plants with them hadn’t occurred to me until now, but could very well be feasible.  

Thanks – I’ve got a lot of studying to do!

[/quote]+1. JAG has ESP. Solves the water issue and farming and the depletion of fish by 2050 as well as the need for a petrochemical reliant system.  

  • Fri, Jul 30, 2010 - 03:26am

    #4
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Re: Can You Feed Your Family With Aquaponics?

The New Alchemy Institute started in the late 60’s with aquaponics. They actually worked with whole integrated systems. They closed up shop in 91. You can still find some of the material on line. The books can still be found. Will Allen has taken their ideas and has been running with them up in Milwaukee.  Check out growingpower.org. and the New Alchemy Institute material at  http://www.thegreencenter.net/

One thing to keep in mind with outdoor fish farms, there are predators like Great Blue Herons that will not only eat the fish but introduce disease. High tunnel green houses eliminate this and you can recycle the water through the greenhouse to water the plants.

Gary Hirshberg of Stoney Field Farm fame was executive director

V

  • Fri, Jul 30, 2010 - 04:47am

    #5
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Re: Can You Feed Your Family With Aquaponics?

JAG

Thanks for the excellent presentation.  This is a fascinating topic I knew nothing about.  It seems pretty fragile though if you can lose all your fish in a few hours if the water stops circulating.  How would you power the pump off the grid if you had a period of cloudy or windless days?  Would it be easy to produce your own baby fish and fly larva etc. to be self sustaining?

  • Fri, Jul 30, 2010 - 09:42am

    #6
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Re: Can You Feed Your Family With Aquaponics?

Thanks JAG!

I’ve been studying this for a while and have even taken 2 trips down to Disney World to go back stage on their Aquaponics ride and speak with the director.  It’s really an absolutely GREAT idea and I’m planning on putting into practice at my compounds.  

It’s really quite amazing to see the dynamics of this process!  And in all reality, it’s not expensive to set up and once you have it, your food processing capacity is astounding!  And you’ll have the best tasting fish around!  

  • Fri, Jul 30, 2010 - 02:46pm

    #7
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Feed Conversion Ratios

Another advantage of aquaponics that I failed to mention in the original post is the feed conversion ratio of fish as compared to other livestock. Unless your “backyard” is large enough to produce free-range/grass fed livestock or you can grow and process your own feed, your going to need to purchase livestock feed. Below is a comparison of the feed conversion ratios for various livestock:

 Thus we can see that fish are much more efficient at turning feed into body weight than other forms of livestock. Whether or not this inherit efficiency translates to reduced feed costs is beyond my ability to calculate at this point. I suspect the cost difference between feeding laying chickens and feeding fish would be significant, but I’m really only “guestimating”. 

One more tidbit, fish waste contains no e-coli pathogens, so contamination of the produce is not a problem.

  • Fri, Jul 30, 2010 - 03:26pm

    #8
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Re: Can You Feed Your Family With Aquaponics?

[quote=Travlin]

How would you power the pump off the grid if you had a period of cloudy or windless days?  Would it be easy to produce your own baby fish and fly larva etc. to be self sustaining?

[/quote]

Obviously you would need a back-up generator (with autostart) to run a high fish-density aquaponic system off-grid. I agree that high fish-densities are not practical, as they cannot be sustained without perfect (aka expensive) mechanical and power support systems. 

For my own system design, I’m looking into drastically increasing the pond size (and surface area/water volume) relative to the fish density. This would allow natural air exchange at the pond surface to sustain the fish population for much longer periods in the event of a pump/aerator failure. The downside to doing this is that is would also drastically reduce the nutrient concentration in the water for the plants. I’m hoping to remedy this situation by mechanically separating the plants and fish. 

The pond would use a conventional filtration set-up that combines mechanical filtration with a biofilter. Daily back-flushings of the mechanical filter (probably a beed or sand type filter) would remove the solid wastes from the pond and deliver them to the planter beds. Rainwater storage would then replace the water taken from the pond during the backwash of the filter. This would also allow me to add nutrients to the plants as needed (ie during fruiting) without affecting the fish, and also allow the use of compost and vermicompost tea as a nutrient source for the plants. Plus, it provides much more flexibility in operating the system as a whole. My brother has a system of similar design to this and its working beautifully.

Regarding the fish and insect breeding, I really don’t know enough to be helpful in this regard.

Best….Jeff

 

  • Fri, Jul 30, 2010 - 04:55pm

    #9
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Re: Can You Feed Your Family With Aquaponics?

 

Fascinating concept Jeff. Thanks for the contribution. I’ll be ordering the CD today and add aquaponics to my (ever-expanding) list of projects. This one should merit a consideration for top priority, methinks.

  • Fri, Jul 30, 2010 - 06:59pm

    #10
    Peak Prosperity Admin

    Peak Prosperity Admin

    Status Bronze Member (Offline)

    Joined: Oct 31 2017

    Posts: 1612

    count placeholder

    Re: Can You Feed Your Family With Aquaponics?

Impressive stuff, JAG.  Thanks.

Aquaponics has been on my mind for some time now.  It’s a ways down my list, but it’s cool to see other people chewing it over.

Viewing 10 posts - 1 through 10 (of 57 total)

Login or Register to post comments