Aquaponics is a closed-loop, recirculating water system in which plants and fish grow together mutualistically. Aquaponics resembles a natural river or lake basin in which fish waste serves as nutrients for the plants, which in turn clean the water for the fish. Tilapia and salad greens or herbs are common fish and plants grown in an aquaponics system. The external inputs to an aquaponics system are fish food, minimal amount of water, and energy for lighting and heating the water for the fish and plants.

Aquaponics is a sustainable, efficient system to raise fish protein and vegetables for human consumption. Aquaponics systems can be located anywhere in the world where there is adequate energy with a minimal amount of water. Aquaponics is particularly suited to arid climates because it uses much less water to grow plants than soil-based systems. In fact, the only water that is lost is evaporation and transpiration from the plants. Although the field of aquaponics is growing world-wide, the capital and operational costs of producing the plants and fish have not been quantified intensively in the peer-reviewed literature. The relationship between the amount of external energy (fish food plus energy for light and heat) to the output (weight of fish and plants) has not been measured well for aquaponics units in temperate climates. The lack of quantification of the input-output has suppressed aquaponics progress because it is difficult to compare the cost of fish and salad greens grown with aquaponics and conventional methods, such as aquaculture and soil-based methods.

The diverse nature of aquaponics and the need to quantify the relationship between input-output presents opportunities for research projects for undergraduate engineering students in Mechanical, Electrical, and Civil Engineering. The following are examples:

Sensors: What type of sensors are ideal to measure air and water temperature, water PH, dissolved O₂, and nitrates?

Thermodynamics: What type of water heating system is most efficient to maintain desirable water and air temperature?

Water Quality: What are the optimal methods to filter out the solid fish waste (feces) and introduce necessary bacteria into the system?

Hydraulics: What size of pump and diameter of pipe are needed to maintain optimal flow rate?

System Design: What are the optimal ratios between fish tank volume and grow area volume? What is the optimal drop in water level between components to utilize the gravity system?

Marquette University College of Engineering is building a laboratory to conduct aquaponics research. The design of the system along with the lessons learned will be presented, along with a detailed list of specific projects for engineering students. Lessons learned from this research will aid the development of aquaponics in temperate climates but also possibly in subtropical and tropical regions