Gardeners Exchange Group Meeting 16 July 2016
Location: Tangy Produce: Aquaponics greenhouse, farm and home of Brian Tanguay and family
Submitted by Julie Neely, GEG Secretary
Aquaponics is the marriage of hydroponics (growing in water- or at least without soil) and aquaculture (raising fish). This combination allows the grower to create a complete and complimentary cycle by raising fish (in this case, tilapia) in the water where the plants grow and are nourished.
Brian Tanguay’s Aquaponics
Brian began his lecture with a brief personal history. He started his farming career as a disenchanted mechanical engineer working in manufacturing but dreaming of growing tomatoes. An article he read entitled “Growing Vegetables Under Water” really started him down the road to Aquaponics. Incredibly, his first experimental fish farm, including fish tanks and plant growing troughs, was located in the basement of the home he was renting at the time. Through trial and error and specific courses, he has mastered his farming techniques and can satisfy customers’ demands for sustainable, all natural, healthy food that is produced in an environmentally friendly way.
Traditional hydroponics is a monoculture technique that relies on very specific, sterile, chemical solutions in which to grow one type of plant very quickly, in large amounts. The byproduct of this technique is large amounts of salt solutions which must be periodically dumped and can be environmentally harmful.
Traditional aquaculture is challenging and costly; the yields must be high to offset operating costs. Fish are raised in large numbers, closely packed together which requires the use of antibiotics and growth enhancing hormones to grow fish fast and to keep the fish alive until they can be marketed. This produces harmful waste water that must be removed disposed of, and is obviously an environmental problem.
Brian’s Aquaponic techniques combine raising fish in large tanks of water and growing plants in troughs filled with the same fish water. He states it is both easier and environmentally safer than aquaculture or hydroponics alone. Brian affirms that the water in the vegetable-growing troughs is safe for the environment and safe enough to drink—and he has drunk from the troughs for skeptics, with no harmful effects. He has had the water analyzed by certified testing facilities in the past.
Basics of Brian’s Aquaponics
- Tilapia fish are grown in tanks of well water; no chlorine can be present.
- The fish waste: exhaled breath, “pee” and “poop” are excreted into the water.
- Bacteria in the water eat the ammonia which is the main constituent of the fish waste products.
- Various bacteria ultimately produce nitrates as their waste product.
- The water from the tanks containing the fish and their waste products, bacteria and their waste including the nitrates, flows into 90-ft-long, 1-ft-wide, 4-ft-deep troughs and eventually electric pumps circulate the water back around to the fish tanks (at a rate of 5 gallons per minute).
- Vegetable plants are grown on rafts floating in the water in the troughs; the plant roots dangle from the bottom of the rafts into the nutrient-laden water where they feed on the nitrates as well as other available micro nutrients and minerals.
- Brian does not use monoculture techniques; he grows a variety of lettuces, fennel, and basil to name a few, all at the same time.
- The water is kept constantly circulating and the fish are grown in a very low density population.
- Seedlings are placed closest to the fish in the circulatory loop and older plants are positioned farther down the trough—the plants on the rafts can be moved around.
- Brian’s plants grow faster possibly because they exert no energy searching for nutrients—the nutrient-laden water is flowing right to and through the roots all the time. He is able to plant on the troughs quite close together because of the optimal growth environment.
- Nitrogen-loving plants—leafy plants (not flower/fruit producers)—thrive in the aquaponics environment, so lettuces, kale, chard, mustard and herbs do well; tomatoes, cucumbers, and peppers do NOT.
- It sounds simple but there are pH issues: fish like pH 8, plants like pH 6, and bacteria like pH 7.
- There are temperature issues and power outages can be and have been devastating.
- Brian sells his plants fresh—the roots are still on the plant and the plant is alive.
- Even plants that require dry, quickly draining soil, like lavender and rosemary, can be grown in water if you provide enough oxygen to their roots. Brian uses “air stones” which release oxygen under water.
- Brian uses air stones to keep his fish and water environment aerobic (not anaerobic); this keeps the beneficial bacteria alive and well.
Brian has permission to raise blue tilapia, which are a hardy, disease resistant, pH tolerant, cold blooded, tropical water fish. Since they are cold blooded they do not harbor harmful bacteria like Salmonella or E. coli, but since they are tropical the water must remain around 60-70 degrees. Brian uses a wood burning furnace to heat his water in the winter. Tilapia are omnivores; they eat soldier fly larvae and/or commercial fish food and they need supplemental iron in their diet. They are also easy to breed. Additionally, tilapia are surface feeders which makes over- or under-feeding easier to avoid. Brian does not sell tilapia to eat as this requires a license and is highly regulated.
Brian uses deep water culture aquaponics, but there are other soil-less methods which use sterile media beds, such as compressed cocoa/coir mesh or pea gravel in addition to water. Eliminating soil removes soil-borne disease. Water is still an essential ingredient as it provides rigidity (turgidity) to plants, enables plant roots to uptake minerals and nutrients and, most importantly, oxygen. Brian’s use of worms in his aquaponics system is still in the experimental stage—they usually just crawl away—maybe due to issues with the oxygen/water/light level?
Brian also has a summertime traditional (but improved) soil garden. He grows a variety of vegetables successfully, using mushroom compost and poultry poop to enhance his soil. Worm tea (worm casts and water) is added to the drip irrigation system which lies under landscape fabric into which his plants are inserted. His very productive 3-acre farm also includes pigs, goats, sheep, one donkey, turkeys, guinea fowl, ducks, rabbits, and chickens.