Our final Tuesday night presentation for the summer was provided by Dave Pennington of SynergyFish and was regarding the field of aquaponics and system design. He also introduced us to "papercrete" a glass-reinforced paper, styrofoam, cement product used to build small domed structures.
We are the only animals on the planet that create waste that does not go back into the natural cycle. We currently use 85% of water for planted agriculture. Dave claimed that nutrients in food have declined by 40%. I wasn't sure what the timeline was or the accuracy of the figure so I did a little checking. Since 1975, based on USDA records there have been a 50% drop in the amount of calcium in broccoli. Watercress down 88% in iron content and cauliflower down 40% in vitamin C content. Click here for more information.
Aquaponics eliminates the concept of waste and elininates the use of chemical fertilizers.
The University of the Virgin Islands, St. Croix offers an intensive course on Aquaponics. Click here for more information.
Aquaponics can be used to produce the following fish:
- Talapia (Mozambique variety)
- Goldfish (easy to grow, size self-regulating)
- Koi (easy to grow, grow throughout lifespan)
- Catfish
- Trout (high temperature sensitive)
- Bass
- Freshwater prawns
- Barramundi/Jade Perch (Australia)
Talapia are the prefered species because they are omnivorous, hearty, easily bred, fast growing and have a mild flavor. The only drawback is that they are sensitive to cold temperatures because they are tropical fish.
Fish:Tank size ratio = 1pound / gallon in rearing tank
Recommended density = 0.25 pounds fish / gallon of water max.
Dave feeds his talapia a combination of organic pelletized fish food, black soldier fly larvae, vegetable scraps, duckweed and other "weeds". He grows his on black soldier fly larvae which are common to Texas. They lay their eggs in waste material, the adults do not eat, sting or bite and it is not a disease vector. They essentially convert garbage into larvae (fish food). When the larvae reach a certain size they stop eating and move away from the food source to pupate into adults. Dave collects them at this time and feeds them to his fish.
For more information on Dave Pennington and Synergy Fish visit: http://synergyfish.com
http://www.youtube.com/watch?v=xRfNw64kP2A&feature=player_detailpage
http://www.youtube.com/watch?feature=player_detailpage&v=k2UzJ9tn0OU
Adam Cohen of Green Phoenix Farms provided a presentation on Aquaponics.
Green Phoenix Farms is a new (1 year old company) based in the Dallas area. Adam has a degree from Texas A&M in marine biology / marine fisheries.
Adam explained what hydroponics (the growing of plants in nutrient rich solutions) and aquaculture (the farming of fish) are. He also discussed the probems with hydroponics and the waste water created by them as well as the expensive, short-life nutrient solutions required to feed the plants that eventually become toxic to the plants. Aquaculture has similar issues like the high nitrogen effluent created by concentrated fish populations and how this nitrogen creates algae blooms which use up dissolved oxygen and cause dead zones in the ocean that cannot support any aquatic life.
Aquaponics takes the downsides of hydroponics and aquaculture and create a closed loop system that produces fish and vegetable produce for consumption and have little negative impact on the environment. The nitrogen rich effluent produced by the fish becomes a natural fertilizer for plants which filter the water for reuse for the fish as well as producing plant material that acts as feed stock for omnivorous fish.
Adam introduced us to Will Allen an aquaponics leader in Millwaukee, MN. Check out a video clip.
He has a 2 acre organic farm in urban Millwaukee where he employs 60 people and composts 60,000 pounds of waste anually.
He also discussed Travis Hughey who proclaims himself an "eco-evangelist". Check out a video clip of Travis.
Aquaponics use about 10% of the water that conventional soil grown agriculture does. It also does not introduce synthetic fertilizers that can bio-accumulate in the environment.
Adam explained the three types of aquaponics systems:
- Ebb & Flow
- Continuous Flow
- Raft Style
Ebb & Flow systems flood the plants root systems and then drain the water to allow oxygen to reach the plants root systems. These systems can be quick-fill/slow-drain or slow-fill/quick-drain systems.
Continuous flow systems keep the roots systems covered with water but require an aerator to oxygenate the water.
Raft-style systems are similart to hydroponic systems in that the plants float on rafts in a nutrient rich solution. This system works well for short plants because taller plants tend to flip over the rafts. Some type of clarifier is need to remove fish waste solids.
Adam then showed us his prototype system that included a 750 gallon fish tank and 60 s.f. of growbed area. The system is designed to produce 100 pounds of fresh Talipia which are omnivorous fish from Africa. His system consisted of an intermediate bulk container (IBC) as a reservoir with a sump pump to push water uphill to the fish tank and (5) 55 gallon plastic food grade drums cut in half length wise. The drums sit on a framework make from standard wood framing purchased at the local DIY center. The overall cost of the system was approximately $1,000. The plant bed material is expanded shale. All piping is PVC as copper tubing is poisonous to the bacteria that break down the fish waste into usable nutrients for the plants.
This aquaponics system is scaleable with a ratio of fish:fish tank of 1 pound of fish for 4 gallons of water and a fish tank:grow bed ratio of 1 gallon of water for every 2 gallons of grow bed. He said that these ratios are approximate but that you must have a minimum of 1:1 ratio of grow bed to fish tank.
Adam also told us about the DFW Aquaponics Meetup group that meets monthly in this area.
Recommended Books:
Urban Agriculture: Ideas and Designs for the New Food Revolution [Paperback], David Tracey Check it out on Amazon.com here.
Guerilla Gardening: A Manualfesto, David Tracey. Check it out on Amazon.com here.
