Aquaponics is the practice of growing plants and fish in conjunction so that their inputs and outputs provide a closed loop ‘ecosystem’ within the greenhouse (See Fig. 5) This brings many benefits, including thermal mass of the water in the fish tanks to store heat, vast reduction in fertilizer use, enhanced crop quality, additional revenue stream from fish, water recirculation and conservation within the facility, and humidification of air for building circulation if connected to a larger building.
Again, these affects can be significant:
Most greenhouses use synthetic fertilizers, subject to price increases when hydrocarbon prices rise. Aquaponics can increase the bottom line by reducing fertilizer costs.
A study of greenhouse grown cucumbers and tomatoes found that aquaponics could increase productivity to a level that net profit over conventional hydroponics.
Fish suitable for aquaponics include tilapia, trout, perch, barramundi, crayfish and bass. The market for Rainbow Trout is lucrative and has room for increased production capacity.
Fertilizers and pesticides pollute water used in typical greenhouse operations, which can require as much fresh water as 800 L/m²/year. This high water intensity can impact permitting and increases costs. Aquaponics puts the majority of water into permanent circulation, so that new water makeup can come from rain catchment, and/or a minimal amount of municipal water.