What is Aquaponics and How Does it Work?

The world is buzzing with talks of aquaponics. Expected to become a $1.4 billion market in the next five years, it has been hailed as the future of sustainable food production. Gardeners are filling their greenhouses with PVC pipe versions, and apartment-dwellers are using mini aquaponics farms to feed themselves fresh greens in homes that don’t even have backyards. But what exactly is aquaponics?

Simply put, aquaponics is a farming practice that combines raising fish with growing plants in one comprehensive system. There are a few different ways to set up an aquaponics garden, and they exist on scales that range from pet store fish tank setups all the way to industrial-sized operations. All of these rely on the basic idea of raising plants and fish alongside each other, and for each other’s benefit.

aquaponics system diagram

Aquaponics Basics

Setting up an aquaponics system is relatively simple. On the most basic level, aquaponics is raising fish in one side of the garden, raising plants in another, and then having a filtration step in between. Because of this simplicity, there are just a few key components necessary for an aquaponics garden to thrive.

Required Components of an Aquaponics System

  • Bins or other containers where the plants and fish will live
  • Piping to connect the bins to each other and to the filtration system
  • Water and air pumps
  • Plants
  • Fish

Some setups require a few more pieces, depending on the local environment where the garden is being built and the type of setup you choose to use. You’ll find more information on the different variations of aquaponics systems in the following section.

Additional Components of an Aquaponics System

Though not required for a basic DIY system, these components can make your aquaponics setup more efficient.

  • Medium for plants to grow in
  • Grow lights
  • Water heater
  • Filtration system

The most complicated part of an aquaponics system is the water chemistry. If the water has too much or too little of any one chemical compound, the fish or plants living in the garden won’t be able to survive. Before the crops and the fish are introduced into the system, it’s recommended to test the water’s pH using a pH meter and adjust until it is near neutral.

what is aquaponics

Types of Aquaponics Systems

Although all versions of aquaponics use the same basic structure, there are several distinct variations: deep water culture, media-based, vertical, and nutrient film technique.

Deep Water Culture (DWC)

DWC is a version of aquaponics where plants float on top of deep tubs of water with their roots free-floating. Plants are held in place by a flotation device, and the water beneath them is aerated either by air pumps or by allowing the water to fall freely into the bins and splash around. The fish and the plants, as with virtually all aquaponics systems, are kept in separate bins. The water moves from the fish area to the plant area and back again continually, being filtered in between with a type of aquarium filtration system to remove solid fish waste.

Media-Based Aquaponics

Media-based aquaponics uses a growing medium that secures the plant in place, but does not contain any nutrients for the plant. Clay pellets are a common medium used in this type of aquaponics setup. The medium acts as a filtration system, as solid waste is unable to move through. When the water is pumped from the fish area to the growing beds, instead of passing through an aquarium filter, the water is directly filtered by the medium.

Vertical Aquaponics

Vertical aquaponics operates without a growing medium. The plants reside in a vertical stack of beds. The water is pumped up to the top of the system and falls on its own back to the bottom. Many DIY vertical aquaponics use PVC pipes. Usually, the fish bins sit at the bottom of the system, allowing the water to flow freely back to the fish from the plants beds above. Usually there is some sort of material in between the flowing water and the roots that allows the plants to suck water through, but stops an excessive amount of leakage. Nutrient-rich water is pumped up continually from the fish bins through a filtration system to remove solid waste and into the stack of growing beds.

Nutrient Film Technique

Nutrient film technique is similar to deep water culture in that the plants grow freely in the water. Instead of being held in place by a flotation device in a deep tub, the growing beds are smaller, and the plants are held in place by the tub itself. In many cases, this looks like a PVC pipe set up horizontally, with the plants growing in holes cut out of the sides of the pipe. The edges of the holes keep the plants from moving. Water is pumped through a filtration system from the fish bins, through the growing beds, and back.

Choosing the best aquaponics setup depends on the amount of available space, the type of plants you intend to grow, and the amount of harvest you are looking to yield.

how does aquaponics work?

How Does Aquaponics Work?

Aquaponics mimics a basic natural ecosystem. The interactions between the fish, the plants, and the bacteria that naturally grow in the water create an environment that is nearly self-sufficient. Once an aquaponics system is set up and lands at a safe pH, most of the maintenance involves occasionally replacing the small amounts of water that evaporate naturally and feeding the fish as necessary.

Let’s take a closer look at what those interactions look like.

When you feed the fish in the system, they digest the food and release solid waste into the water, along with a chemical compound called ammonia. The ammonia comes from the fish urine and is also given off as a by-product of their breathing. One of two things happen to the solid waste. First, the waste can be filtered out of the system, either through a traditional filtration system or through the growing medium, if using a media-based aquaponics system. Second, it can be consumed by a portion of the natural bacteria in the water and turned into different compounds, one of which is more ammonia.

Ammonia is not a compound that will fertilize the plants in the other tubs of the aquaponics system. In fact, too much ammonia in the water can prove deadly. Once the ammonia is released into the water by the fish and the bacteria consuming their waste, a second type of naturally-occurring bacteria consumes the ammonia and converts it into other compounds, one of which is nitrates.

Nitrates make for great fertilizers. At this point, the water is ready to be pumped into the growing beds. The process of fish producing waste and the waste being converted into nitrates is continually happening as soon as the fish are introduced into the garden, meaning the water is always ready to be pumped into the plants.

When the nitrate-rich water is pumped into the growing beds, the plants absorb the nutrients and continue to grow. As the water passes through the plant tubs, the roots of the plants act as a water purifier for the fish tubs, removing the compounds released by the fish and bacteria that could otherwise cause the water to become inhabitable for the fish.

At this point, the cleaned water is returned to the fish tub, where the cycle starts over again.

Achieving the right balance of fish and plants prevents the fish from producing so much waste that the plants can’t remove all of the excess compounds. The right balance also ensures that the plants are receiving enough nutrients to thrive. This means that an aquaponics system can remain in equilibrium all on its own.

What are the Best Fish for an Aquaponic System

Tilapia, trout, and catfish are just some of the best fish for aquaponics. There are a handful of factors to consider when planning out the types of fish for an aquaponic system:

The temperature is important because some systems are indoors and some are outdoors, and air water temperatures can certainly vary.

Size is another consideration. The size of the water container can help determine what size fish would work best. Remember that fish don’t stay hatchlings forever!

Along with the temperature and size, there six other important factors to consider which we go into detail in our best fish article we linked earlier.

The Sustainability Factor

Aquaponics has earned its sustainability title in a few ways. Here’s a list of the major ones:

1. No need for fertilizers

The plants are naturally fertilized by the fish waste, so this eliminates the need for supplemental fertilizers that often cause environmental damage both in harvesting techniques and runoff in traditional soil farming.

2. Saves water

Although aquaponics takes more water during the initial setup, it doesn’t require daily irrigation as is required when growing plants in soil. Since the same water is cycled through the system over and over, the only new water that is added to the system after setup comes from replacing what evaporates.

3. Less space for more food

This is especially true of vertical aquaponics systems. Soil farming only allows you to grow food in one layer, but since you can stack aquaponics growing beds, you can grow multiple plants and raise ediable fish in the same amount of space.

4. Not dependent on the environment

Aquaponics systems can grow fish and plants anywhere there is power to run the system’s equipment. It doesn’t matter if the soil there isn’t able to support a certain crop, or if the weather is too variable, or if the farm sets up in the middle of a big city. Aquaponics systems can be set up indoors, avoiding nearly all environmental limitations, potentially growing food all year round.

5. Reduces the carbon footprint of shipping

Aquaponics farms can set up shop anywhere, so some foods that would otherwise have to be grown on the other side of the country can be grown closer to where they will be sold. If foods can be grown closer, they can be shipped fewer miles, and less emissions will be produced by the vehicles that carry them.

Aquaponics FAQ

What’s the difference between hydroponics and aquaponics?

The hydroponics vs aquaponics debate is a popular one, but the main difference to keep in mind is that aquaponics is just hydroponics with fish. In the previously linked article we go in depth on the subject and help break down which is best for you and your particular use case.

What does aquaponic mean?

Let’s break it down to “aqua + ponic”. Aqua in this sense comes from aquaculture, which is to raise fish or other aquatic animals in a controlled tank. Ponic is Greek for “work”, so putting those two together is where we get aquaponics from. In a similar way, hydroponics is ‘water + work’.

What can be grown in aquaponics?

Similar to hydroponics, almost anything can be grown using an aquaponic system. However, here are the best plants to grow:
– leafy lettuce
– bok choi
– kale
– swiss chard
– arugula
– basil
– mint
– watercress
– chives
– most common house plants
Other common vegetables can definitely be grown but the demands are higher and should be grown in a heavily stocked system. For further reading, check out our post on the best plants to grow with aquaponics.

What is the history of aquaponics?

The history could get long, so we’ll just say that aquaponics has been around since ancient civilizations existed. Aquaponic systems already occur naturally on their own in some areas, and these civilizations realized this and harnessed it for their own use.

The term aquaponics was coined sometime in the 1970s, and that’s when the concept began to pick up some serious steam. Since then, aquaponics has been one of the best sustainable ways to grow plants.

Aquaponics is an interesting type of farming and worth looking into. If you’re interested in aquaponics, try making your own DIY aquaponics system. It’s fun! Sustainable farming is on the rise as we all try to reduce our carbon footprint, and aquaponics is an effective, and fun way to do that.

High Tech Gardening