What is Aquaponics?
In its simplest form, aquaponics is the growing of plants with fish poop......seriously. In its most complex form, aquaponics is the art of hydroponically culturing plants and raising fish by creating an environment in which a nearly self sustaining ecosystem teaming with a plethora of microorganisms coexisting symbiotically with the plants and fish by continuously mineralizing and oxidizing toxic fish waste into plant available nutrients that the plants readily assimilate while simultaneously "cleaning" the water for the fish. Sounds like pretty simple stuff, right? My reason for such a stark contrast between definitions of aquaponics was to highlight the fact that, on the surface, aquaponics seems pretty simple, but that doesn't mean that there isn't a whole lot of really cool science going on beneath the surface. Let's break this down step by step to give you a basic understanding of how aquaponics works.
For this explanation, I will be using a basic flood and drain media bed (FDMB) system as an example. This is because this is the most common type of backyard system. For all other forms of aquaponics, which I'll cover on another part of this site, the end goal is the same; utilize fish waste as a source of nutrients for hydroponically culturing plants. The only differnece is those systems will have a different layout of components, usually catered towards growing one specific type of crop. But for this example, we're going to focus on the FDMB aquaponic systems.
As you can see in the above picture of a FDMB, there are two main components; a fish tank and a grow bed. A submersible pump in the fish tank pumps the fish waste laden water into the grow bed above it. In a FDMB, you can think of the grow bed as not only the vessel in which you will culture your plants, but also as the filtration unit for your fish tank. The grow-bed provides both mechanical filtration, removal of solids, as well as biological filtration, the oxidizing of the fish produced ammonia into nitrate.
Fish produce waste in two main forms, solid fecal matter (poop) and ammonia. Lets start off talking about the stinky stuff. The fish effluent in the fish tank is pumped into and percolates through the grow-bed. The solids are trapped in the interstitial spaces of the media. This prevents solids from returning to the fish tank. Over time, beneficial microbes will break down and mineralize the solid fish waste, releasing plant available nutrients into the system.
The other form of waste produced by the fish is ammonia (NH3). Ammonia is a metabolic waste product generated by the fish as they consume food. Ammonia is toxic to fish and can be lethal if left untreated. As the fish tank water is pumped into the grow-bed, it is met by beneficial microorganisms that colonize the grow-bed. These are known as Nitrifying bacteria.
These Nitrifying bacteria are responsible for converting the ammonia produced by the fish into
nitrate (NO3). This process is called nitrification. Nitrification is a 2-step process which is primarily performed by two species of nitrifying bacteria; Nitrosomonas and Nitrobacter. These bacteria are all around us in abundant levels. They exist in the air, water and soil. The Nitrosomonas bacteria are responsible for converting the ammonia (NH3) into Nitrite (NO2). Nitrite is also toxic to fish and needs to be further oxidized into Nitrate. The Nitrobacter bacteria are responsible for converting the Nitrite (NO2) into Nitrate (NO3). Nitrate is non-toxic to fish, even at high levels, and is the form of nitrogen most used by plants.
Once the bacteria have broken down and converted the fish waste into a plant available form, the nutrients are taken up by the plants through photosynthesis. As the plants remove the nutrients from the water, they are essentially filtering it by removing what was once a toxic waste product produced by the fish. At this point, the now clean water is ready to return to the fish tank. Once the water is returned to the fish tank, the entire process begins again.
So to recap, the fish produce waste in the form of solid matter and ammonia. The fish waste laden water is pumped into the grow-bed where the microbes and plants are located. Beneficial microorganisms breakdown and oxidize the fish waste into plant available nutrients. The plants take up the nutrients as they grow, filtering the water for the fish. The now clean water is returned to the fish and the process begins again.
Now that you understand the basics of how an aquaponic system works, it's equally important that you understand the benefits associated with growing your food aquaponically. There are very many reasons, and different people might have different reasons why they love their aquaponic system so much. But the following is my list of some of the top reasons to grow aquaponically:
Aquaponics allows you to naturally grow your own nutrient dense food.
Once an aquaponic system is set up, it is very low maintenance.
Plants are automatically watered and fertilized.
No harsh chemicals or pesticides are used.
Aquaponics uses a fraction of the water used in soil based agriculture.
Plants can grow twice as fast as they would in soil.
There are no soil born diseases.
Weeds are not a problem in aquaponics.
You are growing two crops (plants and fish) with only one input (fish feed).
Provides self sufficiency as well as piece of mind knowing from where your food comes.
Most importantly, aquaponics is a whole lot of fun!
There are numerous reasons to grow aquaponically. There are even more ways to set up your system. With aquaponics, the sky is the limit. An aquaponic system can be 20 gallons or 20,000 gallons. It can be made from a repurposed bath tub or from a brand new polyethylene tank. No matter what route you go, one thing stays the same; aquaponics is one of the most efficient, productive, natural and enjoyable ways to grow your own nutrient dense food.