Aquaponics combines aquaculture with water treatment engineering and hydroponics, a soilless nutrient delivery plant cultivation technique. This method has shown promising results to produce high-quality fish and crops in a controlled environment, where outside risks associated with traditional agriculture are negated. Aquaponics’ ability to grow robust hemp and cannabis plants provides an encouraging alternative to traditional production of these high value crops.
A commercial, decoupled aquaponics test system was built for growing high-nutrient demand crops. The recirculating aquaculture system (RAS) component consists of two 300-gallon fish tanks, a deep two-walled clarifier, a bead filter, a biofilter, two sump tanks, and two mineralization tanks. Nutrient-rich water from the fish tanks passes through a clarifier and bead filter to remove a majority of solids from the system. After solids removal water enters the biofilter, the filtered water returns to the fish tanks and is added to three aerated, decoupled sumps that each feed Dutch bucket hydroponic rows. Three different media types were tested: light expanded clay aggregate (LECA), coco coir, and a peat-perlite mix. An additional row of hemp was grown hydroponically in coco coir as a control group; nutrient solution was mixed daily to proper concentrations for hemp production. Sludge from the RAS is aggressively aerated in a two-stage mineralization process in order to enhance breakdown of solid waste into bioavailable forms for plant uptake, and is then added back into the RAS. Temperature, pH, electrical conductivity, dissolved oxygen levels, water macro and micronutrients, and leaf tissue samples were tested to more deeply understand the health of the fish and plants.
Results are still in progress but clearly show the viability of hemp production in an aquaponics system, along with fish production and the ability to translate production for cannabis. While required initial costs, components, and expertise may be greater compared to traditional hydroponics, aquaponics is a zero discharge and fully organic production method. After harvesting, flower biomass, terpene levels, CBD and THC levels will help aid the comparison of performance of each media.