Growing plants and fish through aquaponics is easy on the environment as well as financially easy. Aquaponic systems do not use any chemicals, and they require about 10 percent of the water used in regular farming. The system is closed — that is, once filled with water, only a small amount is introduced into the system afterwards to replace the evaporated water. But how can water-based systems use less water than conventional farming?
The answer is the continuous reuse and recycling of water through naturally occurring biological processes. Basically, fish waste produces natural bacteria that convert waste such as ammonia into nitrates. This nitrate is then absorbed by plants as a source of nutrients. The basic principle of aquaponics is to utilize waste.
Let’s see the process step by step:
- Fish that live in aquaponics tanks excrete waste and breathe ammonia into the water. Ammonia is toxic to fish in high concentrations, so it must be removed from the fish tank to keep fish healthy.
- Water containing ammonia is processed to harvest beneficial types of bacteria such as Nitrosomonas and Nitrobacter. Nitrosomonas convert ammonia to nitrite, while nitrobacter converts to nitrate. Both of these nitrates can be used as plant fertilizers.
- Nitrate-rich water is fed to hydroponically grown plants (plants grown without soil). The plant is placed on a bed that sits in a tub filled with water, and the water is increased by nitrates harvested from fish droppings. The plant’s bare roots hang through holes in the beds and dangle in the nutrient-laden water.
- Plant roots absorb nitrate, which acts as a nutrient-rich plant food. This nitrate, which comes from fish waste, algae, and rotting fish feed, will build up to toxic levels in the fish tank and kill the fish. But instead, they serve as fertilizer for plants.
- Hydroponic plant roots act as a biofilter — they remove ammonia, nitrate, nitrite, and phosphorus from the water. Then, the clean water is recirculated back to the fish tank.
Since fish waste is used as fertilizer, there is no need for chemical fertilizers. The money and energy needed to make the chemical work is saved. In fact, the only conventional cultivation method used to operate the aquaponics system is feeding the fish.
Now you know how aquaponics works on a biochemical level. But what kind of fish is best for this system? And what plants thrive in it? Let’s find out.