What is Aquaponics?
Simply put, aquaponics is the combination of two food production systems; aquaculture, the growing of fish, and hydroponics, the growing of plants in a soil-less medium using nutrient rich-water.
By themselves, both aquaculture and hydroponics produce nutrient-rich waste water. This waste-water needs to be filtered and cleaned before being reused which can become quite costly.
In some cases, it’s just dumped into drains and waterways causing significant damage to the local environment and ecosystems.
When these two growing methods are integrated, they create a symbiotic partnership that eliminates the need to waste vast amounts of wastewater and creates the water saving polyculture we call Aquaponics.
What Powers Aquaponic Systems?
Most folks will tell you that it's the fish that run an aquaponic system, but it's truly the naturally occurring nitrifying bacteria that do all the hard lifting.
These nitrifying bacteria live in our atmosphere and are the "waste" converters in the nitrogen cycle that’s continually going on all around us.
You can grow fish without plants and plants without fish but once you bring the two together, you need these little workhorses to make an aquaponic system become the productive polyculture that it is.
As such, I consider these microscopic workers to be the backbone of the system, much as fertile soil requires a healthy colony of microorganisms and fungi to grow healthy plants.
More about those helpful fellas in a tick.
How Does Aquaponics Work?
To begin with, we’re going to start with the fish as they produce all the nutrients in this system.
The fish consume their protein-rich food, assimilate some of its nutrients into their growth and excrete the un-assimilated nutrients as waste products.
The waste will contain many elements vital for plant growth, with the bulk of this waste being ammonia.
The majority of the ammonia is excreted through the gills of the fish, with the rest leaving their cloaca at the tail end along with the solid waste.
Ammonia is toxic to both fish (and plants to some extent) if left unprocessed and this is where the bacteria come in.
The wastewater moves from the fish tank through to the plant or hydroponic side of the aquaponic system.
Here it enters the grow beds (AKA Bio Filters), and the nitrifying bacteria get to work oxidising it.
Aquaponic Nitrogen Cycle
The first lot of bacteria that get to work are predominantly from the Nitrosomonas genus. They get their energy by oxidising the ammonia (NH4) the fish produce into nitrite (NO2).
From there the nitrite (NO2), which is also very toxic to the fish, is oxidised into Nitrate (NO3) by the second group of bacteria that come mainly from the Nitrobacter genus.
Nitrates are not dangerous to fish in the levels seen in a well-maintained backyard Aquaponics system.
The plants then use the nitrate and the processed clean water is now free to flow back into the fish side of the aquaponic system to be loaded up with more ammonia for the bacteria to feast once more.
Benefits of Aquaponic Growing
One of the biggest reasons many are drawn to aquaponics is that it is a growing system where harsh toxic chemicals, like pesticides and herbicides, cannot be used due to the sensitivity of fish. This is a major drawcard for those striving to produce food as “Organically” as possible for their families and friends.
Some folks like to grow using aquaponics to reduce the amount of ocean-caught fish they consume.
A few are worried about heavy metal build ups like mercury while others have concerns with the way the oceans are being managed and see growing their own as a responsible way to obtain fish.
Aquaponics uses a fraction of the water used in conventional plant growing methods. The water is recirculated through the whole system over and over with the only losses occurring through transpiration of moisture from the leaves and a small amount being lost to evaporation.
Due to the design and layout of most systems, the grow beds are quite often at a reasonable height off the ground. This makes aquaponics ideal for people with mobility issues & have problems working with conventional garden beds on the ground.
Aquaponic systems can also be used as an indoor growing system just like hydroponics. I have seen many systems set up in garages or basements by those in cold climates, have very little yard space or live in apartments.
Aquaponic systems also tend to have virtually no weeds pop up in them unless seeds are blown in by the breeze or deposited by passing birds. We do however get a lot of self-sown lettuce and other greens pop up in the grow beds but they are always a welcome site.
Like hydroponics, the plants can grow a lot faster than conventional soil beds. This is especially apparent with leafy crops like lettuce, Asian green, parsley and sweet basil. This makes aquaponics an ideal growing system especially if you would like to utilise a small amount of space to grow as much food as you can.
One of the biggest pros I’ve got from starting aquaponics is having to learn something new. While running a backyard aquaponics system isn’t rocket science it does require you to do a bit of research. You'll need to learn about keeping fish, plant requirements + you’ll very quickly start to pick up a few handyman skills along the way as you’re building and tweaking your system.
Build Your Own
DIY Aquaponic System
The "How to Build Your Own Backyard Aquaponic System" has a couple of easy to follow videos that will help you build your own small Backyard aquaponic system.
One is a small system made from a recycled 200L blue drum and the other, from a recycled 1000L IBC.