Aquaponics combines hydroponics with aquaculture. Hydroponics is the science of growing plants without soil in nutrient-rich water. The nutrients are exactly tailored to nourish and meet the growth requirements of the plants. Plants need nitrogen, phosphorus, potassium, and a variety of micronutrients to thrive.
Normally, in a hydroponics system, synthetic fertilizers added to the water provide all of these essential nutrients. In an aquaponics system, the fish provide nutrients in the form of their excrement. This waste contains nitrogen in the form of ammonia (which is excreted by fish due to its toxicity), along with nutrients like phosphorus and potassium. Nitrifying bacteria that live in the gravel in the fish tank and on the tank walls can convert the ammonia first into nitrites and then to nitrates.
The water in the tank, which contains ammonia, nitrites, nitrates, phosphorus, potassium, and other micronutrients, is continuously pumped into a grow bed where the plants are located. The plants remove the nutrients from this water, and nitrifying bacteria in the grow bed (working together with the tank filter) clean the water by converting excess ammonia into nitrates, which plants use to grow. The clean water is then sent back into the fish tank. The grow bed and plants act as a biofilter, cleansing the water so that the fish remain healthy. In smaller, backyard aquaponics systems, the grow bed sits on top of the fish tank and the cleansed water from the grow bed drips back into the tank. In aquaponics, the fish, plants, and beneficial bacteria all depend on each other to live.
The option of an aquaponics system inside that of an automatic aquarium can be considered, as it is very feasible. Since an automatic aquarium system aims to eliminate as much human effort needed to maintain the aquarium in good condition, the bio-filter system created by the plants and the nitrifying bacteria will benefit greatly to the cleanliness of the tank. The conversion of ammonia to nitrates not only give plants suitable nutrients for growth, but also eliminates the toxic ammonia from the fish tank. Ammonia not only affects the fish if too much is in their bodies, but also when there are high ammonia concentration in the water. Fish will be under stress, and will suffer from ammonia poisoning. Prolonged concentration over a few days can result in fatalities. Therefore, the aquaponic system will improve the overall quality of the aquarium water, and reduce fish casualties.
The build cost of a grow bed is relatively cheap, less than $100. It is made of readily available materials, thus can be constructed DIY if preferred. The nitrification bacteria are also in large supply to those aquaponic or aquarium owners, and should be found in most aquarium stores.
In aquaponics, the fishes, plants, and bacteria are interdependent on each other. When fish excrete waste, it provides a source of food for the bacteria. Their digestion process creates nutrients in the form of nitrates for the plants. Plants then use the nitrates for growth, removing it from the water, hence cleansing it. Such a system if self-sustainable, and easily managed, which is further enhanced by the inclusion of an auto-feeding system for the fish. Also, bacteria levels after a short period, can reproduce rapidly, enhancing the conversion of ammonia to nitrates, and thus provide better filtering efficiency.