Aquaponics refers to any system that combines conventional aquaculture (raising aquatic animals such as snails, fish, crayfish or prawns in tanks) with hydroponics (cultivating plants in water) in a symbiotic environment. In normal aquaculture, excretions from the animals being raised can accumulate in the water, increasing toxicity. In an aquaponic system, water from an aquaculture system is fed to a hydroponic system where the by-products are broken down by nitrifying bacteria initially into nitrites and subsequently into nitrates that are utilized by the plants as nutrients. Then, the water is recirculated back to the aquaculture system.
The Science of Aquaponics
The science of aquaponics is as much fascinating and forwarding-thinking as it is simplistic and age-old. Aquaponics has really only been making waves over the last few decades despite the practice dating back thousands of years. The reason behind this trend is a heightened interest in organic foods, sustainable living, and self-sufficient lifestyles.
So what is aquaponics and how exactly does it work? Let’s delve into the science behind aquaponics.
What is Aquaponics?
In simple terms, Aquaponics is the combination of aquaculture and hydroponics. As you may know, aquaculture is the raising of fish while hydroponics is the practice of growing plants without soil. Aquaponics blends the basic elements of both of these practices into one integrated, symbiotic system. Its appeal is apparent; you have an efficient and ecologically-sound way to grow vegetables and raise fish for human consumption – all in one self-sustaining ecosystem.
Aquaponics systems are closed-looped and recirculating. While neither hydroponics nor aquaponics uses soil as the growing medium, their main difference lies in the way plants are fed. Hydroponics relies on synthetic (chemical) fertilizers as its nutrient source, whereas aquaponics relies on fish waste (yes, fish poop) to provide an organic food source for the plants. This difference makes aquaponics an appealing option for conventional organic gardeners who have never gone soilless.
As the grower, your active role in this ecosystem is to feed the fish, monitor the system (pH, water temps, water levels, etc.), and supply the energy for the pump, lighting, and water heater (depending on your design and location). You also get to eat the fruits of your labor. Very symbiotic indeed!
Aquaponics: How it all Works？
1. Ammonification: Fish are fed fish food. They then excrete their waste in the form of ammonia. High concentrations of ammonia are toxic to fish, so it must be removed from the fish tank.
2. Pump: A pump removes the fish waste from the fish tank and cycles the ammonia and water to the grow bed. Grow beds are filled with grow media (usually expanded clay pebbles), the soil-replacing substrate.
3.Nitrification: Beneficial bacteria – which colonize in grow beds/grow media – break down the ammonia and converts it into nitrites. Worms can also be used to assist in this process.
4.Nitrification: Bacteria further convert the nitrites into nitrates.
5.Assimilation: Plants absorb the converted nitrates as their food source (fertilizer).
6.Bio-filtration: Plants roots act as a natural bio-filter to clean the water. The grow media also acts to filter the water as it passes through the grow beds. In theory, the water in the system should remain clean enough so that the fish can survive without the need to ever change it (although this is not always the case).
7.Oxygen: Air pumps/air stones are often used to maintain sufficient oxygen levels in aquaponics systems. The design of an aquaponics system may also provide some oxygen by way of gravity (as water recirculates between the grow bed and fish tank and mixes with air).
For the water quality detection of the co-growth system, the common parameters include water temperature, pH, dissolved oxygen, ammonia nitrogen, nitrite, nitrate, total phosphorus, total nitrogen, etc. These parameters can reflect the content of nutrients in the water body, the concentration of harmful substances and the pH of the water body.
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