How Do Aquaponics Systems Work?

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Soilless gardening methods have become increasingly popular in recent years. One of those methods is aquaponics, which cultivates fish and plants together in a recirculating system. If you are one to consider this alternative farming technique, you might wonder, “how do aquaponics systems work?” 

Aquaponics is a recirculating system that involves growing plants in media beds and using fish as their source of fertilizer. In this method, the fish tanks capture the excrement waste from fish (or other aquatic creatures), which will be sent to the grow bed where naturally-occurring bacteria break them down as plant food. In return, plants filter out the water and send it back to the fish tank.

Within the aquaponics system, there are three primary system designs that can be implemented to grow plants and raise fish. Understanding how all these aquaponics systems work helps you choose the best design that fits your needs. This article will explain the basics of how aquaponics work and the three system designs used in both commercial and backyard aquaponics.

The Biological Components of Aquaponics

Aquaponics combines aquaculture and hydroponics to form a sustainable, recirculating soilless system. In aquaponics, there are three components that keep the system running:

• Plants – These are not only grown for your personal consumption but also to help filter out waste from the fish tanks. After the water gets filtered out, it goes back to the fish tank, safe and clean to be reused.
• Aquatic creatures – Fish are not the only animals grown in aquaponics. Other creatures that have been used successfully include crayfish and shrimp. The aquatic animals used for the system play a vital role since they produce the waste that will, in turn, become fertilizer for plants. Selecting the best fish to use can help you have maximum growth output for your plants and fish. 
• Bacteria – Beneficial bacteria are responsible for breaking down waste into plant food to help them thrive. In an aquaponics system, bacteria naturally grow and are usually settling at the bottom of the tank or on the grow media.

All these components work together and have mutual relationships in an artificial ecosystem. Once you have all these components and have set up your system, there will be minimal effort or little maintenance required from your part.

Different Aquaponics Systems

There are different ways to set up your aquaponics system. The three most common ones are:

• Media Beds
• Nutrient Film Technique (NFT)
• Deep Water Culture (DWC)

Media Filled Beds

Growing in media-filled beds is the most popular system design, especially for small-scale aquaponics. This is because it’s much easier and simpler to set up. In this method, plants are supported using soilless media, like expanded clay rock, or gravel. Media-bed growing requires a continuous flow and drainage of water. 

Also called flood table, media beds can be built above the fish tank or to its side. They can be made from wooden crates or heavy-duty plastic tray. If you’re using a wooden pallet crate, it may require a stand to support its weight.

 To read more about media bed systems, click here.

Nutrient Film Technique (NFT)

In NFT designs, nutrient-rich water is pumped in narrow channels, usually made of PVC pipes. Plants grow in small cups and are supported with some form of media (usually clay pebbles). In doing this technique, it is important for the water flow to be as thin as a film (hence the name) rather than flooding as it travels through the channels.

Since this technique is not exposed to air, putting up a biological filter may be necessary. This way, beneficial bacteria can develop and carry out its role in breaking down fish waste and converting it to plant nutrients.

NFT is more complicated to set up compared to media beds, which is why they’re more suited for commercial rather than backyard growing. However, there are hobbyists that have successfully used NFTs even in their own backyard. 

Note, however, that NFT may not be a suitable technique to use for all plants. Leafy greens are popular with NFTs since they’re generally lightweight and don’t have invasive root systems. Alternatively, plants that have big roots systems may be better suited for media beds.

For a more detailed discussion on NFT, check out this article.

Deep Water Culture (DWC)

Deep Water Culture is also known as Raft System or Deep Flow, which means that plants are placed in rafts (usually made of foam) and allowed to float. Just like NFT, it is a popular method for commercial aquaponics.

In raft systems, the plants are placed in net pots, which are then lined up on foam boards. The roots hang down in the water as they absorb the nutrients needed for rapid growth. The nutrient-rich water continuously flows from the fish tank to a raft tank, where all the foam boards are floating. The water then goes back to the fish for reuse already clean. In most cases, the raft tank is built separately from the fish tank. 

For a more in-depth discussion on DWC, click here.

Aquaponics Fish

Proper selection of fish is important to have a thriving aquaponics system. Fish and plants must have similar needs, particularly when it comes to pH and temperature requirements. The similarities may not be that exact but it’s best to go for the closest match to have a successful setup.

In addition, the selection of fish will also depend on the overall purpose of your aquaponics system. You can either raise fish that are edible or not. If you are a hobby grower who wants to raise fish for consumption, along with harvesting fresh crops, then you will likely choose fish such as the popular tilapia. On the other hand, if you’re mainly a commercial aquaponics grower, inedible, ornamental fish like koi and goldfish would do.

Other Important Components

Besides bacteria, and the right pairing of plants and fish, site selection and water pumps are just as important to your overall system.

To survive in a an artificial ecosystem and produce the best yield, fish and plants require high dissolved oxygen levels. This can be achieved by aeration, with the help of air pumps. However, installing an air pump is not the only way you can supplement the oxygen requirements of fish and plants. To read more about air pumps and how to choose the right one for your setup, click here.

Meanwhile,  the fact that aquaponics can be setup anywhere makes it more advantageous than traditional farming. Still, you need to consider the proper location for your system, whether you’re building one for commercial growing or as a hobby. There are factors to consider such as stability of the surface, exposure to and protection from weather elements, presence of sunlight and shade, and utilities, among others.

To read more about the guide in selecting your aquaponics site, click here.

Conclusion: How Do Aquaponics Systems Work?

Aquaponics may involve various techniques and system designs to grow plants and fish, but all of them share one thing in common: the system uses fish waste as fertilizer for plants in a recirculating system. Whatever technique you use, make sure you understand each of them and determine which one best suits your purpose.