The word Aquaponics comes from a combination of two words: AQUAculture and hydroPONICS. This duo forms a symbiotic relationship between plants and aquatic animals.
The plants use the wastes from the aquatic animals as fertiliser therefore they clean the water by removing the nitrates. These nitrates have been previously converted from ammonia and nitrites by beneficial bacteria in the system.
Strangely, ammonia is the number 1 killer of aquarium inhabitants world wide, but in this situation everybody wins. Well, until you see the size of those fish that the aquarium/pond has been growing. Yet, you don't have to keep edible fish or crustaceans, as you can always have gold fish or Koi in your pond.
