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 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.
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:
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 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).
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.
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.
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
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!
+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.
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
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?
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!
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.
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?
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.
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.
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.
It would seem as though an additional benefit would be conservation of water versus conventionally grown produce inasmuch that water consumption would be limited to loss through transpiration (vapor loss through leaf surfaces) as opposed to loss through evaporation and percolation through the soil strata that is experienced through conventional agricultural means. This would provide a huge benefit in drier states like here in California. In your study thus far have you seen any indication that this is the case?
Thanks again for your effort on this thread.
The only thing that worries me about this stuff is that there's too much technology... what happens when a pump dies and you can't get a replacement, or the grid becomes totally unreliable and you rely on backup batteries which will inevitably become impossible to replace? And of course the cost of initiating such a system on a scale large enough to feed a family must be pretty high...
At least with an in ground system, YOU can do all the work instead of relying on what are basically still FF slaves (electricity - whether renewables generated or not). And that work, once your system is in place is minimal really. Yesterday I mucked out the goat shed and got five wheelbarrow loads of geat compost/semi compost, and it took me all of an hour and a bit to do....
BTW, Omega 3 FA's can be had from free ranging grass fed chickens....... unlike the crap meat from supermarkets.
Your absolutely correct about how water efficient the system is, as the only loses are via evaporation and plant transpiration like you stated. I really goofed by leaving this out of my original post, I'm a little ashamed to say that I overlooked this major advantage of aquaponics probably because where I live we get 50+ inches of rainfall a year and its not really an issue for me.
If I live in a dry climate, I would think it would be nice to also have another 1000 gallons of water available just as a back-up in a crisis. A decent water filter should make the water very drinkable. Heck, the guy in this video just drinks it without a filter, lol. Notice how the cut-away shot hid the fact that he spit it out
What CD (or DVD) did you buy btw?
I totally agree with your assessment within the context of the worst case scenario. But I don't really share your worst case scenario, and I'm comfortable with my assumption that mechanical technology (and electricity) will be around for the rest of my lifetime. I should be clear that I think aquaponics is at best just a component of a larger permaculture system, however.
PS. I have to raise my beer to the brain trust "down under". Us americans look like a bunch of dongos compared to your mates like Mollison and Steve Keen. Auquaponics seems to have quite the following down under as well.
Thanks for the praise.....
Actually, this guy I know is building a new house within sight of where I'm typing, and he is planning a large aquaponics system, so I'll be able to keep an eye on how it all pans out... now this thread is started, I'll even keep you posted, though I have no idea how long it will take him to get going.
Regarding the water efficiency issues discussed here, I can vouch to the fact Permaculture is probably as efficient as Aquaculture. Loads of mulching and well fed organic soil doesn't lose much water at all, and we only start watering if it hasn't rained for a week or two, depending on temperature, and then we only water the plants individually.
There are more microbes in a hand of fertile soil than people on Earth. The soil needs the moisture. All wealth derives from the Earth specifically healthy soil which requires moisture. The anthropogenic view of the world is what got us here. The beauty of permaculture is it is holistic , along the lines of what indigenous people did naturally. But if you wish to engage in that discussion you need to go to the basement.
As far as Americans being dongos I suggest you look at my previous post on this thread where you will find links to The New Alchemy Institute and will Allen's growingpower.org . He took the NAI's work and ran with it. I would also direct you to the Rocky Mountain Institute and Amory Lovins work.. Also Joel Salatin has done remarkable things at Polyface farm.
Us americans look like a bunch of dongos compared to your mates like Mollison and Steve Keen.
If I'm a dongo for being grateful that my ancestors chose not to emigrate to a country that was a former penal colony (for good reason) and chose not to live where a good percentage of everything that crawls or swims will kill you (and where even the freaking mammals can be venomous),
call me Dr. Dongo.;-)
Oops, I see I misspelled the word drongo in my previous post.
It's drongo, not dongo, which I guess proves my point!!!
A patient of mine from Australia a few years back told me it basically meant "dumbass". Mike must have got a good laugh from that one.
that Australian wildlife scares the crap out of me too, lol.
Ah...beat me to it (re: "drongo")...I lived in NZ for a year and always loved that word -- feels really chewy coming out of one's mouth.
As for the Australian wildlife, I lived in Sydney for ~ 3 months and I'll say that the most dangerous wildlife are the 2-legged mammals down the pub ±10 minutes of last call. I learned to be standing near an exit (or already gone) when that moment rolled around.
Maybe I patronized the wrong sort of pub...
Will definitely keep an eye on this thread going forward. As a landlocked New Englander, the idea of raising tilapia really appeals to the fish-lover in me regardless of whether or not supermarkets will become a thing of the past.
Viva -- Sager
I find the whole aquaponics subject fascinating. I wonder though if raising tilapia this way will produce lower omega-6 and 9 fatty acids levels and higher omega-3 levels than farm raised tilapia?
My longtime dream has been a little closer to nature though. Basically, take a natural ecosystem with forest, meadow, swamp, pond, stream or river, etc. and manage it and cultivate it to have nature grow most of my food for me and selectively harvest it, whether deer, bear, rabbit, squirrel, game birds, waterfowl, fish, snapping turtle, crawfish, maple syryp, etc. Have been looking for the right property for a while now but have still not found it.
If your looking to grow the fish with the highest omega 3 content (and best ratio to omega 6, 9) then the Australian Jade Perch is your best bet. The Queensland Jade Perch has a whopping 2400 mg of omega 3 FA per 100 gm of flesh. I do think you would have to supplement their fish food with some greens and insects to achieve anywhere near this level in aquaponics however. Perhaps purslane leaves would be a good supplement. I have read that some people raise this fish in the states, but I haven't found a source yet.
Maybe you did Sager....... but you are absolutely right, way more people die at the hands of other people than any snake or spider or shark! I've scuba dived among sharks (even pushed one away that got too close once!) without any problems. No, I'm not a drongo! We have some of the deadliest snakes in the world here (Taipans and Eastern Browns) but they leave you alone unless you corner one (happened to me once in the shed) and all you do is slowly back off. They give you plenty of warnings if they're not happy with your presence...
I only know one person who was bitten by a brown snake (at least 40 years ago) and he's still with us aged 76!
Can't remember when was the last time anyone got bitten by a spider in the media, though last year was a bad year for shark attacks, probably because so many more people go swimming at dangerous beaches. More people drown than get attaked by sharks....
That's interesting. But it's Australian ... there must be something on it that's poisonous.;-)
I'm assuming they're not too cold hardy though. I need something that can live underneath ice. Largemouth bass have always been a favorite but they're higher up on the food chain. May have to find a pristine enough water source for a trout pond which isn't too hard to do around here.
Your original post contains Youtube trailers for Murray Hallam's DVD on Aquaponics. On every veiwing a pop-up would appear on screen to tout the DVD. However, now upon returning I see no pop-ups. Either someone's messin' with me or I been hangin' around Sager's pubs to long.
Feed your Family? If I lived in AZ and had the GardenPond.org guy's system - I'd be raising the lobster size crayfish - another Aussie import. See the link to Red Claw Farmiing.
We raised them inside the house before and they are prolific breeding crayfish with gorgeous coloring. They also happen to be on my "To Do" list to get started on our hobby farm in one of the outbuildings. The small ones can be eaten as prawns and the large ones are small lobster size (more like very large prawns). And they live in fresh water, eat anything and are a delightful pet.
The only trouble we had was they liked to crawl out of their kiddie pool and into the chicken coop. They are more fun than a barrel of monkeys!
My 2 cents. . .I'd support my family on the system that guy has. . . and feed them too.
Alright, this AP system is just a little too fancy
Its called the "Sun Curve" by Inka Biospheric Systems (whose site is unfortunately under construction). The pump is powered by both PV and micro-turbine wind power. The plants are grown in a sheet medium known as bio-quilt. I think these guys, based out of San Francisco, had a little too much money to invest in this project.
It is pretty.
Looks like something outta "Barbarella" -- which ain't necessarily a bad thing. I suppose if one is wealthy enough to have one's resilience be both functional and futuristically beautiful....
Of course, one could spend the same amount of money for a system 3x the size -- and feed the neighborhood. Probably more important in the grand scheme of things... But then, I'm a Community Building nut... <wry grin>
OK, I'm doing some serious thinking about creating my own aquaponics system - on the supremo-cheapo, of course. Buying a ready-to-assemble kit for a few thousand bucks is out of the question due to shipping costs and due to my innate desire to frustrate myself endlessly doing things myself. I have a few questions for the brain trust:
Does anyone know anything about pumps? How do I know what size pump to get?
I plan on using the flood technique. How much water do I need to filter through the growing beds at a time? How often do I need to do so? I'm looking for a percentage-answer on the first question and a daly frequency to the second.
How does the start-up balancing process work? By that, my assumption is one has to start with the fish. I suppose the fish water needs to be filtered through the growing beds without plants in them initially, to get the bacteria growing. Is this right? How do I know when there are enough bacteria so I can start adding plants?
I think I've learned all that is possible from the general-overview type info available on websites I've found and youtube videos. I now need detailed, hans-on info.
It seems aquaponics is huge in Australia, as all the books and DVDs I've found are only available through Down Under outfits. I do have a DVD and a book on order, but from Australia to Costa Rica might take a few weeks and I am itching for info.
By the way, this system seems very easy to maintain once you get it going. And in my area, where I go through 4-5 months of no rain, I need something that recycles as much water as possible. Aquaponics is definitely the ticket for me, and throws off fish as a bonus.
Thanks any and all who can help! If I find nobody can help, I will be keeping detailed notes so hopefully I can post everything I learn back on here at some future date.
One more question: What exactly is "expanded clay". All I know is this is the fill material used in the growing beds that is used to support the bacteria colonies that convert urea into nitrates. It is also used in regular hydroponics, and there are all sorts of manufacturers for the stuff. The definition for it I've found is:
A material made from common brick clays by grinding, screening, and then feeding through a gas burner at about 2700°F (1482°C), thus changing the ferric oxide to ferrous oxide and causing the formation of bubbles.
A material made from common brick clays by grinding, screening, and then feeding through a gas burner at about 2700°F (1482°C), thus changing the ferric oxide to ferrous oxide and causing the formation of bubbles.
If I go to a brick factory and ask for their wasted brick pieces and crumbs, will that be "expanded clay"? Seems to me like it would, but I am in layman's land here and have no idea what I'm talking about. I ask because although I'm sure I could get "official" expanded clay here somewhere, it will probably cost a ton of money due to it being imported, or merely marketed and priced to the naive. On the other hand, expanded clay being what it is according to the definition I found, it should be easy to find here if I only look in the right places. There are a few brick factories here but before I go, I wanted to know if their waste is what I'm looking for.
Do a search for LECA
Lightweight expanded clay aggregate.
Clay is fired in a rotary kiln and it pops like popcorn.
Some is round balls and some looks like 1/4" grey lava rocks.
I used it as a base layer on the green roof I had on my last home. Great stuff. It allows the root structure to actually live in the holes in the aggregate and since it holds moisture deep within the rock, wind and heat don't dry it out fast.
I recently started subscribing to Murray Hallam's blog (it's free by the way). He just posted a new aquaponics design, which he terms CHOP, mark 2 and which you can read about in his blog. I am already considering implementing it in my system and recommend that anyone considering an AP system give this design some consideration as the advantages are important.
Speaking of which, I finally got my system up and running up last weekend. If you want to check it out, and follow my trials and tribulations, go to Farmer Brown's Aquaponics. I have my set up at a farm and I only go there on weekends, but so far (according to my caretaker), it seems to be working. I'm so excited about this whole thing, I'm already thinking of the next two systems I want to build!
DTM, and anyone else worried about pumps and fittings and complications - it's not at all that complicated or finicky. I highly recommend it. It looks daunting at first, just like 3rd grade math did at one point. You will quickly get over it!
Thanks JAG for turning me on to this stuff!
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