Aquaculture North America

Swimming against the tide

September 24, 2018
By Mari-Len de Guzman

At the heart of southwestern Ontario, one crop producer has mastered the art of aquaponics, where healthy tilapia are grown alongside premium quality cannabis.  

Green Relief has been growing marijuana for medicinal purposes since 2016. From the beginning, the company has made it its mission to find sustainable ways to grow their crop.

“Aquaponics started for us as a small greenhouse addition to the back of our house with a self-contained system,” explains CEO Warren Bravo. “We were going to grow vegetables for our family all year round, at a greenhouse that we can walk up to.”

Bravo’s 50-acre property in Flamborough, Ontario, is home to Green Relief’s 32,000-sq-ft indoor grow facility. Construction is underway for an additional 220,000-sq-ft building that’s expected to produce 45,000 kgs of cannabis annually. A third building is also part of the expansion plan, which will provide an additional 180,000 sq ft of production space for the company.

Green Relief is one of at least 114 licensed cannabis producers in Canada, but its growing technique is unique in the industry. Using aquaponics technology developed with Nelson and Pade, in Montello, Wisconsin, Green Relief uses fish waste carried through a recirculating water system to deliver nutrients to the cannabis plants. Around 300 tilapia are grown in circular tanks located inside the grow room. Upon maturity, the fish are harvested and donated to local food banks.

“The idea of having an aquaponics system at the house has morphed into what you see now as North America’s – or the world’s – only high-production cannabis facility using aquaponics,” Bravo states.

Fish for feed

Put plainly, aquaponics is a method of growing food that uses a closed-loop process that mimics the ecosystem.

Green Relief’s aquaponic structure is powered by a recirculating aquaculture system containing 18,000 gallons of water continuously recycling through the system, explains Derek Bravo, operations manager at Green Relief.

Fish start out in the system as fry. They stay in the nursery with young cannabis plants. As both plant and fish grow, they are transferred to the main grow room where they stay until ready for harvest, at which point they go their separate ways – the cannabis flowers go to the dry room for processing and the tilapia go into Second Harvest trucks for delivery to local food banks.

All the magic happens in the grow room. Derek Bravo explains they use only organic fish feed to grow the fish. Fish waste is then produced, which flows through the tank into the clarifiers. The clarifiers are the first level of filtration, consisting of a light screen in the middle. Heavy solids then sink to the bottom of the tank, while the finer solids flow through from the clarifier into the mineralization tank to be broken down further.

The water then goes into the bioreactor.

“That’s where the aerobic bacteria is created with heavily oxygenated tank with a bunch of bio beads where the bacteria lives on,” Bravo explains. “Once the beads get too covered with bacteria coating, it will break off, flow into our system that attaches to one of the grow beds.”

In this process, nitrification occurs and the resulting nitrate becomes nutrient for the plants.

“The plants just sit on styrofoam, and they just float on the water. Their roots go down the water and uptake nutrients whenever they need them,” Bravo says.
The water then flows back to the fish tank and the cycle repeats.

Ecosystem approach

CEO Warren Bravo notes the significant amount of research and the huge learning curve that went into the process of building Green Relief’s aquaponics facility. Bravo and Green Relief co-founder Steve LeBlanc both come from the construction industry. Their knowledge of buildings and structures only took them halfway through achieving their goal of establishing a sustainable cannabis production company that leaves as little impact on the environment as possible. The rest, they had to learn.

The pair spent over two years doing research on aquaponics, speaking with known experts on aquaponics and sustainable agriculture around the world. Among them was Nick Savidov, senior research scientist of the aquaponics program at Lethbridge College in Alberta.

“Aquaponics is an integrated multi-trophic production system,” explains Savidov.

In aquaculture, an integrated multi-trophic system follows the concept of a natural marine ecosystem, where one species produces the waste or byproducts that become sustenance to another organism within the ecosystem.

“Natural ecosystem does not have waste; everything is getting utilized, so that the waste product of one component – such as fish manure ¬– become feed stock for another component, which are beneficial microorganisms such as bacteria, fungi, protozoa and so forth. The plants are fed by the water, then the water goes back to the fish,” Savidov says.

The aquaponics approach is different from the traditional monoculture approach in agriculture – such as hydroponic or soil-based crops – which have largely become unsustainable, he says.
In an aquaponic system, “recirculation” is key, Savidov says. “Water becomes not just a habitat for plants, fish and the nutrients and microorganisms. Water becomes a carrier, a link that ties together all those components.”

Although in its infancy, aquaponics is beginning to gain traction in the food production industry (see sidde bar: The business case for aquaponics). A recent decision by the U.S. Department of Agriculture not to reject aquaponics as an organic technology opens up a huge potential for aquaponic-based food production facilities to get certified as organic, Savidov says. He hopes Canada would follow suit.

Another advantage of aquaponics over traditional methods of food production is that every component can be naturally grown without any use of chemicals or additional fertilizers.

“In modern agriculture we use resources such as fertilizer. All fertilizers come from finite resources… from raw deposits which are not limitless,” Savidov notes. “What happens if we exhaust all raw deposits?”
Savidov acknowledges fish feed may be the biggest cost factor in an aquaponic system, but even that, in the long run, can be addressed by a self-sustaining, advanced system that increases plant output with less amount of fish feed. The key is in the aerobic bioreactors.

“Use of aerobic bioreactors allows 100 percent nutrient recycling in an aquaponic system and improves the crop output in the system,” Savidov explains.

Around 300 tilapia are grown in circular tanks located inside the grow room. Upon maturity

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