Table of Contents
3C Aquaponics Basics
3Ca What I have Learned
3Cb Next Steps
3E Reflections on my Process
Op 3 is a consolidation of my learnings and practice in aquaponics as a viable, scalable method for high density organic food production.
3C Aquaponics Basics
What is Aquaponics?
Aquaponics is the symbiotic growing of plants and aquatic animals in a re-circulating environment. It combines hydroponic farming with aquaculture. Water is cycled between fish tanks and vegetable growing areas. Fish waste acts as a natural fertilizer for the crops. Plants and beneficial bacteria scrub ammonia and other nitrogenous compounds from the water, making it safe for the fish.
Why use Aquaponics?
Aquaponic systems can operate with near zero environmental impact by using off grid passsive and active solar energy. These are closed loop systems which eliminate or minimize use of fossil fuels, recycle all waste to produce high-quality hormone-free fish and organic vegetables, all without the use of artificial fertilizers, pesticides, or herbicides.
Aquaponics is a water-wise growing method. It generally requires 90% less water than conventional vegetable gardens, and 97% less water than standard aquaculture methods.
Aquaponics is versatile and adaptable. Systems can be built on just about any scale and designed to fit in almost any space.
The Nitrogen Cycle - The Magic of the System
Aquaponics makes use of the nitrogen cycle to create a balanced productive system. Plants receive their nitrogen in a fixed form such as nitrate ions, ammonia, or urea. Animals get their nitrogen from plants in the case of herbivores, or from animals that have eaten plants, in the case of carnivores. Nitrifying bacteria facilitate the conversion of waste products to forms of nitrogen utilized by plants.
What can we grow?
A wide variety of fish and other aquatic organisms can be cultured in aquaponic systems. Freshwater, herbivorous or omnivorous fish are ideal choices for their sustainability, ease of feeding, and a more efficient conversion from feed to fish. Leafy crops such as lettuce and herbs work very well in small scale aquaponic systems. Fruiting plants such as tomatoes, cucumbers, and peppers may require larger systems with deeper growing areas and in some cases more nutrients.
Media Bed with Hydroton
TYPES OF THE AQUAPONIC SYSTEMS
In 2010 I took my first aquaponics workshop with the Ecolife Foundation in Escondido CA. where I learned about the NFT systems; and was introduced to media beds, hydroton, and bell siphons. I built a media bed system and began to learn firsthand about this thing called Aquaponics. More recently in February of 2013 I attended a 7-day commercial aquaponics and solar greenhouse training in Tennessee where I learned about deep water raft technology and solar greenhouse construction from Tim Mann of Friendly Aquaponics. Tim shared with us what he and his wife Susanne had learned over five years of operating a commercial aquaponics farm in Hawaii much of which was from making mistakes and learning from them. I am currently living In New York City where I have just installed my Manhattan Mini Farm, a 2 foot square table top system in my 400' apt.
There are three primary methods practiced in aquaponics:
Nutrient Film Technique (NFT),
Media Grow Bed /Ebb and Flow, and
Raft or Deep Water culture.
Nutrient Film Technique (NFT)
Nutrient Film Technique or NFT is presently the most popular technique used in hydroponics, and is easily adapted for use in aquaponics. With this method a thin layer of water containing the dissolved nutrients from the fish tank is pumped through the bare roots of plants in a watertight gully, or channel. The depth of the re-circulating stream is very shallow, allowing for an abundant supply of oxygen to reach the roots of the plants. The main advantage of the NFT system is that the plant roots are exposed to a continuous supply of water, oxygen, and nutrients. A downside of NFT is that it has less buffering against interruptions in the flow, e.g. power outages, but overall it is a very productive technique.
2) Grow Bed / Ebb and Flow
Another method widely used by backyard growers is the Grow Bed aquaponics. The growing area is a wide deep container with good surface area. This container is filled with gravel, LECA, or other soilless growing medium and the vegetables are planted directly into the medium. These systems are often designed to provide water to the plants intermittently. A water pump controlled by an adjustable timer is used to provide water to fill the tub in an “ebb-and-flow” manner. As the pump runs the grow bed is saturated with water. When the pump is off the water slowly drains out. As it drains oxygen is pulled through the roots.
An alternative means of providing water in an ebb-and-flow manner is with the use of a bell siphon. A bell siphon is a mechanism for drawing water from a higher container to a lower container. Siphons can be adapted to control the flooding and draining of grow beds in an aquaponics setup. In this usage, they are called auto-siphons -- siphons that can start and stop in response to changing water levels.
Specifically, bell siphons and loop siphons are two useful, and commonly used, techniques for this application. Bell siphons can also be used in biological filters to create a wet/dry environment beneficial to aerobic nitrifying bacteria.
Raft or Deep Water Culture:
Raft aquaponics is the technique used most frequently in large-scale commercial aquaponics. With this technique, the plants are grown on perforated rafts, usually made of Styrofoam or similar buoyant material, which float in dedicated water tanks.
The roots of the plants are often bare and constantly in the water. This is a highly productive method, but when combined with High Density fish production, requires intensive biological and mechanical filtration to keep the water clean and clear of any solids waste. Low Density fish production greatly minimizes added filtration needs.
There are two primary types of filtration used in aquaponic systems: biological filtration and mechanical filtration.
Biological filtration or bio-filtration is the most critical for providing proper water quality, and the well being of the fish. In bio-filtration, naturally occurring aerobic bacteria convert the toxic ammonia (NH3) produced by fish, decomposing fish waste, uneaten food, and dead plant matter into nitrite (NO2) (also toxic) and then to relatively non-toxic nitrate (NO3). Bio-filtration is achieved in a number of ways in these systems, but all work on the same basic principal of moving oxygenated water through an inert material with high surface area in which the nitrifying bacteria colonize.
Note: In Low Density Aquaponics systems where less fish are used to produce more vegetables, the plants become the bio-filtration and thereby eliminating the extra technology and expense. The Low Density method of deep water raft culture has proven to date to be the most economically sustainable method for commercial food production.
One type of bacteria called Nitrosomonas converts ammonia to nitrite, a second bacteria called Nitrospira converts that nitrite into nitrate which is in turn utilized by plants, or in the case of aquaponics, by the vegetables you are growing.
The Initial Cycle:
These beneficial bacteria are ubiquitous and will eventually colonize where there is adequate oxygen and nutrients. As with a freshly set up aquarium, a new aquaponics system must first be “cycled” or "inoculated" prior to adding a large number of fish. Cycling is the process of building up sufficient nitrifying bacteria colonies in the bio-filter to optimally handle the waste produced by the fish population. This is achieved by adding just a few fish to the system initially. These fish will add enough ammonia to start the cycle. Gradually the ammonia level will rise and as this happens the bacteria (Nitrosomonas) begin to make use of the ammonia, converting it to nitrite. As the ammonia peaks, other bacteria (Nitrospira) begin to convert the nitrite to nitrate. The cycle naturally stabilizes in four to five weeks, after which more fish may be added to the system. This is best done on a gradual basis – slowly building up to capacity.
There are also alternative “fishless” inoculating methods and head-start bacteria cultures available that can help to bolster and speed up the cycling process.
With aquaponic systems using grow beds, the media that the plants are rooted in, usually gravel or LECA (porous clay balls sometimes called Hydroton), also acts as the biological filter. In NFT systems utilizing individual grow pots with small amounts of grow media or those employing the high density raft technique with roots growing directly in the water, a separate bio-filter is required.
Mechanical filtration is the removal of solids waste before broken down by biological processes. This may be achieved by passing the water through a fine material such as a foam sponge, filter sock, or other synthetic barrier, which traps the solids and is manually removed and cleaned on a frequent basis. The manual removal of organic solids benefits the system by taking some of the demand off of the biological filtration, reducing the amount of oxygen used by bacteria in the mineralization and nitrifying processes. This is important, as your fish need that oxygen as well. If there is too much solid waste in the system – uneaten food, plant matter, etc., the dissolved oxygen may drop to dangerously low levels. Good oxygenation is extremely important in Aquaponics both for fish and plants!
In aquaponic systems a water pump is used to move water from the fish holding tank through the filters to the plant roots and back to the tank. If multiple tanks or barrels are used, the water may also be diverted to circulate through all of the tanks consistently, or a separate pump can be used for this circuit. The water pump(s) should be of quality and power to provide an even strong flow through all of the tanks, and consistent water flow to the roots of the plants. Providing strong water movement through the fish tanks reduces dead spots and improves overall oxygenation.
NOTES ON EQUIPMENT
Basic Parts and Supplies required
Grow Trays or NFT Channels
Growing media ( clay balls, gravel, sand)
Plumbing ( pipe, tubing, fittings, clamps)
Biological Filter (plants or medium to grow bacteria)
Water Heater (if needed)
Air pump / Diffusers
Net Pots (for NFT) and raft systems
Lighting (if indoors)
Fish Tanks, Ponds, and Barrels
A variety of containers may be utilized to hold fish, including aquariums, plastic storage barrels, prefab tanks and lined ponds.
Grow Trays and NFT Channels
Specialty growing trays and NFT (nutrient film technique) channel are available through hydroponic and agriculture equipment suppliers.
Common and inexpensive materials may also be adapted to work for this purpose. For example, plastic cement mixing trays and plastic storage containers of appropriate size can work well as both fish tanks and growing trays, and rain gutter downspout is easily adapted to accommodate growing pots for NFT systems. Timber Bamboo works but needs replacing more often.
Anuenue (rainbow) Inspiration
My First Media Bed System
Aquaponics as a method for producing high quality food in a controlled environment has both intrigued and inspired me since I first heard about it in 2009. When I first learned of aquaponics I wondered why more people weren't doing it because it seemed like a fantastic solution for producing good clean, nutritious food.
Over the past two years I have studied different types of aquaponics with different teachers all the while observing what worked well and what needed improvement. Many people get very excited as I did when they learn of aquaponics and it is my desire for this piece of work to provide useful information gained from my research and experience to those of you interested to read it.
The world of aquaponics is evolving rapidly as we learn and share with each other. I hope you will find what follows useful and become inspired to have your own aquaponics experience!
Teryl Chapel April 12, 2013
2x2 Manhattan Mini-Farm
Tilapia (Oreochromis spp.)
Catfish (Ictalurus spp.)
Crappie (Pomoxis spp.)
Silver perch (Bairdiella sp.)
Golden perch (Macquaria sp.) (Australia)
Yellow perch (Percaflavescens)
Various ornamental tropical fish such as guppies, tetras,
swordtails, mollies, mosquito fish and many others.
* Please note that some fish species are regulated, and in some cases restricted, in parts of the country. Check with your local fish and wildlife regulatory agency to learn about the specific ordinances and any required permits for your region.
A wide variety of plants may be grown aquaponically. Here are a few plants that do particularly well in these systems:
Green leaf, red leaf, and other leafy lettuces, Pak choi (bok choi), Swiss chard, Arugula, Basil, Mint, Watercress, Chives, Mizuna and other micro-greens
Many common tropical plants / house plants
Some fruiting plants may have higher nutritional demands and do best in heavily stocked, well-established systems, such as:
Tomatoes, Peppers, Cucumbers, Beans, Peas, Squash, bananas, pineapple, wheat
3Cb Next Steps
My Next Steps.
In Partnership with Harlem Seeds I will be constructing a 128 square foot demonstration DWR aquaponics system on the main rooftop at the Kennedy Center in Harlem which is in the Northern part of Manhattan.
This is demonstration system will be the initial phase of a “Pilot” rooftop Urban Teaching Farm and will be used to help raise funds for the Solar Greenhouse and phase 2 expansion for the farm. I am working with the local Slow Food chapter to assist with fundraising and plan to implement a crowd funding campaign.
http://www.fiveboroughfarm.org I recently took a day long workshop sponsored by the Five Borough Farm project and Design Trust for Public Space NYC where we learned about implementing measuring and documenting practices related to urban farming. There is much useful information on their website and I will be participating in Phase Two of their project, working with other Urban Farmers collaborating and sharing data.
I am currently working on a collaborative Output Packet on Solar Greenhouse design and construction for Scalable Aquaponics Food Production with Daniel Brodellake, fellow Gaia associate. Stayed Tuned!
3Ca What I have learned
What I have learned about applied commercial aquaponics
1. In my opinion, the best systems are DWR (deep water raft) systems with the vegetable troughs located right on the ground, parking lot, or roof for the following reasons:
A. DWR systems are less expensive to build by a factor of three to four than media-based flood and drain systems. You don't need to build sturdy (and thus expensive!) raised tables or fill them with Hydroton or other expensive media. Deep water raft systems are cheap because the supporting structure (the ground) is cheap, and they are filled with water (instead of gravel or expensive clay balls).
B. Raft systems have far lower labor costs to operate than raised media-based systems, because you can remove entire rafts from the vegetable troughs to harvest and replant them at waist height on sawhorses or other supports at a convenient central “harvesting facility”. This is the reason that these troughs don’t need to be at waist level; the rafts are easily moved, even when full of vegetables. This is a huge labor savings.
Here’s how it works: the lightweight newly replanted rafts go into the troughs at the far end from where you harvest. Now, every time you harvest and remove rafts from the "harvest" end of the troughs, the remaining rafts float down towards the harvest end of the troughs, so that when they're mature they are as close as possible to where you are doing the harvesting process. This way, you don't have to walk to the vegetables to harvest them, they float to you.
I experimented with a small media bed system for a year and a half before determining these types of systems had no advantages for commercial growers.
Commercial aquaponics farms growing in media beds face several extra challenges. One is the fact that workers will be cutting warm lettuce into a basket a couple of hundred feet from the processing facility. This is because the lettuce in the media beds doesn't "come to the processing facility" the way lettuce in rafts floats down to the end of a 100-foot long deep water trough.
This means two things for the farmer: one, when harvesting lettuce in a media bed system, the harvester can't put more than three or four pounds of lettuce into a basket or container without the lettuce on top damaging the quality of the lettuce on the bottom. This means frequent trips from the harvesting area to processing area are required. Consequently labor time/costs are increased here as compared to a deepwater raft system, where the lettuce comes to the harvesting area alive and with roots intact.
Also, even if the worker makes frequent trips with small amounts of lettuce (more labor/money) you may still end up with lower quality lettuce than that which comes from a deepwater raft system. Because of the longer distance and time between the harvest area and the processing area in large media bed systems, your lettuce is warmer for much longer. It will decrease in quality because of this time spent warming up, and no one can predict exactly how much. On a hot day, you may experience both of these; increased labor costs AND reduced quality.
There are other concerns worth considering when comparing systems for commercial applications: the cost per square foot of systems.
When we compare the cost of materials and labor, a waist-high supported media bed system costs about four times as much as a deepwater raft system supported on the ground. These are serious concerns for a commercial aquaponics venture.
If you have a small system, using media simply means you will be working a little more for your food, so it is not a huge concern. As soon as you scale up these factors multiply exponentially
Depending on how much water your media-based system has in it, and how much of your media area is exposed to warm air during flood and drain cycles, this could mean higher system water temperatures that result in poorer growth, less healthy plants, lower yields, or all of the above. In an extreme case it might mean that a system has to be shut down or be artificially cooled in really hot weather if the water heats up too much.
You can also get the opposite effect in cold weather: the media bed will get cooled by the cold ambient air, sometimes to the point where the water gets so cold that it kills the fish in the system.
Bonus the DWR systems allow you to grow freshwater prawns for an additional income from the system. This is impossible to do in media-based systems."
One thing to keep in mind The most profitable plants will be very specific to your locale. Not only do different plants grow differently in different locations and climates, but "profitable" also depends on what is worth the most in your market. It takes two steps to determine "what plants are the most profitable"; the first step is to do a test grow in your aquaponics system. This will give you information on what grows well and what doesn't, in your area.
The second step is to test-market your vegetables from your test grow, in your area. This is something you need to research personally. You may get better than standard prices for your produce, for you will find that aquaponic produce is generally much higher quality, with better taste and longer shelf life than its soil-grown counterparts, which brings premium prices for it.
In this "Introduction to Aquaponics" I have shared what I have learned about the different types of AP systems, how AP works, what can be grown, and the difference between "hobby" AP systems and applied AP for sustainable food production. I have also discussed what sytems I think are best for Urban applications and briefly touched on controlled greenhouse environments powered by active and passive solar. It is my hope that this article will empower you with enough information to encourage you to have your own experience with Aquaponics. Remember it is better to start small and learn from small mistakes than from big expensive ones. We have much to discover about this thing called Aquaponics which allows for much opportunity in design and implementation.
Tim Mann of Friendly Aquaponics says “We have figured out a lot about growing food with aquaponics in the past eight years and we still only know of fraction of what we will know 10 years from now.”
3E Self Reflection
My learning process with Gaia U has taken me full circle with aquaponics starting as the focus of my degree, fading in to the background during my time at Terravita Springs, and returning very charged after my experience at Findhorn and my move to New York City. Once I found the “juice” ( thanks to the help of my advisor) my energy and enthusiasm for producing this work has shown up dramatically making my process much more exciting and enjoyable. It feels much like an experience I had many years ago during the time in my life when I lived in Hawaii and danced traditonal Hula with a men's hula group;
I remember the day after a year of working hard and practicing Hula when suddenly during a performance I realized without thinking the dance was dancing me and I had became one with the dance. So it is with my learning process, as the forced effort slips away I feel I am becoming one with my work and the process of documenting it.
Going to Findhorn and Moving to New York where two significant pattern- interrupts in my life process which have given me an opportunity re-engage with my world more aligned with myself and with a renewed sense of purpose.
I am appreciative for Nala my advisor pushed me to refine this OP even after I thought it was done. Once I got over the initial frustration of having my work returned after I had turned it in thinking it was pretty good, I really am greatful for the opportunity to make it better.
Friendly Aquaponics good open source for information on proven commercial aquaponics, solar greenhouses, tilapia hatcheries, DIY manuals, and training programs
Ecolife Foundation third world aquaponics,conservation
Aquatic Eco source for pumps, netpots and other supplies
Mid Year Presentation more information on aquaponics as integrated eco-social design
Sony Digital Video camera
HTC android smart phone