Aquaponics is a combination of aquaculture (the growing of fish and other aquatic animals) and hydroponics (the growing of plants without soil) in one recirculating environment. In aquaponics, the fish produce waste that the nitrifying bacteria convert into nutrients for the plants. Plant roots absorb these nutrients to thrive. In return, the plant roots clean and filter the water for the fish to live.
How Does Aquaponics Work?
In aquaponics, the plants are grown in the grow bed, and fish are placed in the fish tank. The nutrient-rich water from the fish tank that contains fish waste is fed to the grow bed, where billions of naturally occurring beneficial bacteria break the ammonia down into nitrites and then into nitrates.
Plants absorb these nitrates and other nutrients to help them grow. The plant's roots clean and filter the water before it flows back into the fish tank for the fish to live. The fresh, clean, and oxygenated water recirculates back to the fish tank, where the cycle will begin again.
Benefits of Aquaponics
Here are some benefits of an aquaponics system:
- Aquaponics is a sustainable and intensive production system.
- It offers two potential incomes from fish and plant production.
- Aquaponics is water efficient.
- It does not require soil or large space of land.
- Do not use fertilizer, pesticides, and other chemicals because they might affect the fish in the system.
- There is no soil involved in aquaponic systems, so it removes the debilitating task of weeding and digging.
- Aquaponics allows you to grow food all year round by regulating the temperatures as per what you are growing and using greenhouses.
- The produce harvested from aquaponic systems is organic and free from chemicals.
Here are some disadvantages of aquaponics:
- It might be expensive to set up and build.
- Daily maintenance is required.
- It needs knowledge of fish, bacteria, and plant production.
- It requires a reliable electrical source.
The History of Aquaponics
Aquaponics can be traced back to the Aztec Indians around 1000 AD, who grew plants on rafts on the surface of Lake Texcoco. While the Aztecs' chinampas in Mexico are believed to be the basis of modern aquaponics, the people from eastern Asia (China, Indonesia, and Thailand) were also thought to be among the earliest practitioners of aquaponics.
In Asia, farming involved growing rice in paddy rice fields with the help of fish such as catfish. The wastewater from the catfish tanks was used to fertilize the rice fields and other crops.
While the ancient people of Asia and Central America produced the concept of growing plants and fish together, the existence of modern aquaponics that is getting popular these days started in the 1970s. The development of modern aquaponics is attributed to the works of the New Alchemy Institute and North Carolina State University by Dr. Mark McMurtry.
The New Alchemy Institute researches the creation of ecologically derived human support systems for renewable energy, aquaculture agriculture, landscapes, and housing.
Part of the research was focused on aquaculture, where they experimented with raising edible fish in above-ground tanks. The fertile waste water from the tanks is then used to feed the crops in the greenhouse.
Dr. McMurtry was inspired by the works of the New Alchemy Institute and started research on aquaponics. In the mid-1980s, with Prof. Doug Sanderson, the first closed-loop aquaponics system was created.
In their aquaponics system, the wastewater from the fish tank was used to irrigate crops such as cucumbers and tomatoes in the grow bed filled with sands. The sand served as the bio-filter of the water that passes through it. The water then returns to the fish tank filtered by the sands,
What Type of Plants Can You Grow in Aquaponics?
Almost all plants can be grown in aquaponics. However, plants also have different nutrient, space, and light requirements. So, to choose the best plants and achieve the optimum result from your aquaponic system, keep in mind the factors mentioned above.
Depending on your aquaponics setup. The plants that grow best in aquaponics systems include vegetables, leafy greens, small root vegetables, microgreens, fruiting plants, herbs, and flowers.
Here is the list of plants that grow best on a specific aquaponics method.
- Media Based Aquaponics System: lettuce, tomato, ginger, eggplant, cucumber, and any plants that will fit your grow bed.
- Raft System: lettuce, basil, kale, cabbage, swiss chard, bok choy, mint, watercress, and other small rooting plants
- Nutrient Film Technique (NFT): lettuce, strawberry, spinach, parsley, dill, and other small rooting plants.
What Fish Species are Best for Aquaponics?
Fish play an essential role because their waste becomes the natural fertilizer for the plants. To achieve a maximum growth output from your fish, select a hardy fish best suited to your location, climate, and needs.
The most common fish raised in aquaponics systems are:
- Edible fish: tilapia, carp,catfish, trout, largemouth bass, salmon, yellow perch, bluegill, jade perch, barramundi
- Ornamental fish: goldfish, koi, tetras, guppies
- Other aquatic animals such as shrimps
Types of Aquaponics System
There are the four main types of aquaponics systems, which we will discuss below.
1. Media Based Aquaponics System
Media Based, or Flood and Drain is the most common aquaponics system. A media based uses a grow bed or container filled with grow media (usually gravel, lava rock, or clay pebbles) to plant the crops.
The grow bed is periodically flooded with water from the fish tank through a bell siphon so that the plants can access the nutrients. The water drains back into the fish tank, where a new cycle begins.
All waste is broken down in the grow bed. Sometimes worms are added to the grow media to help break down all the waste. The media based uses the fewest components, and no additional filtration is needed, making it easy to operate.
2. Raft System
The raft system is also known as Deep Water Culture or Floating System. In a raft system, the nutrient-rich water circulates through the long canals, usually at a depth of about 20 cm, while rafts (polystyrene or foam board) float on top.
The plants are grown on the raft boards supported within holes by net pots. Plant roots hang down in the nutrient-rich, oxygenated water, where they absorb oxygen and nutrients to thrive.
The nutrient-filled water flows continuously from the fish tank through the filtration process, then to the raft tank where the plants are grown, and finally back to the fish tank. Most often, the raft tank is separate from the fish tank.
3. Nutrient Film Technique (NFT)
The Nutrient Film Technique (NFT) is a hydroponic growing technique adapted to aquaponics because of its simple yet effective design that works well in some environments.
In the NFT method, the plants are grown on long, narrow channels. A thin film of water continuously flows down each channel to provide plant roots with water, nutrients, and oxygen.
Like the raft system, the water flows from the fish tank through filtration components, through the NFT channels where plants are grown, and then back into the fish tank. A separate biofilter is required in NFT because there is insufficient surface area for the beneficial bacteria to live.
Components of an Aquaponics System
Fish play an essential role in aquaponics because their waste acts as a natural fertilizer for the plants. To achieve a maximum growth output from your fish, select the best fish for your system and know how to care for the fish in your system correctly.
Choosing the best plant to grow in your aquaponics system is essential for your system's overall success. So select plants that are easy to grow and well suited to your location.
Until your new system is fully established, avoid planting nutrient-hungry plants like tomatoes and stick to easy-to-grow plants like leafy greens, lettuce, and herbs. Nutrient-hungry plants require a lot of nutrients, so wait until the fish in the system is larger before you start adding tomatoes, peppers, and other fruit-bearing plants.
Plants in Aquaponics are planted in the grow bed, pipes, or floating rafts. If you're using grow beds, ensure that the grow bed container is strong and the grow medium is deep enough to hold your plants.
When planting your plants, ensure that the base with the plants is sturdy enough to keep them when they grow. Using net pots is recommended because it allows the plant roots to absorb ample nutrients and securely hold the plant. If you're planting in a floating foam, make sure it is lightweight, buoyant, and can hold the plants upright.
The bacteria in an aquaponics system can be present in the biofilter, grow beds, and fish tanks. Bacteria convert fish wastes into nutrients absorbed by the plants. So it is essential to maintain a healthy bacterial colony in your system.
- Fish Tank - The fish tank is the home of your fish and one of the most important materials of the aquaponics system.
- Grow Bed - Will hold your plants and grow media. The grow bed can be PVC pipes, floating rafts, or any food-grade containers depending on your system.
- Grow Bed Support - Frame that will support the weight of your grow bed.
- Sump Tank- Optional. Using a sump tank will depend on the design of your system.
- Plumbing Pipes and Fittings - It depends on the type of your grow beds, system, and other factors.
- Bell Siphon - A bell siphon is required for a flood and drains media bed.
- Water Pump - The water pump size depends on your desired tank exchange rate and several grow beds.
- Aerator and Air Stones - These are used in the fish tank and media beds.
- Grow Lights - Optional. Grow lights are mainly used in indoor systems.
- Heater - Optional. Using a water heater will depend on your location, fish species, and target water temperature.
- Grow Media - You can use clay pebbles, expanded shale, gravel, and other inert media for a media-based system.
- Monitoring System - Optional. It depends on your situation and how you want to manage your system.
- Timers and Controllers - These are used for controlling the lighting, pumping, and temperature.
Factors that Determine a Successful Aquaponics System
The first and most important factor in having a successful aquaponics garden is ensuring that the fish are kept healthy. All fish need oxygen to survive and thrive, and therefore a good aeration system is essential.
The temperature of the water is also quite critical for fish to survive. Any abnormal rise or drop in temperature can cause problems for the fish. You should check to see which temperature is best for the type of fish you have.
The pH of the water must be between 7 and 7.5, which is neither acidic nor alkaline. If the PH rises or falls, it is essential that the cause is quickly remedied. This may be that the fish is overfed and that the uneaten fish feed disintegrates and collects at the bottom of the aquarium.
By regularly testing the water quality, you ensure any problems that arise be resolved long before they have had the chance to cause actual damage.
Getting Started with Aquaponics
1. Building Your System
Once you have all the materials needed for your aquaponics system, you can start building your system based on your specifications and design. Test your system to ensure there are no leaks and the flow rate and drain rate work well.
2. System Cycling
Before stocking your system with fish and plants, ensure your system is healthy by cycling to establish the beneficial bacteria. The cycling process converts ammonia (fish wastes) into nitrates necessary for the plants to thrive in an aquaponics system.
Cycling starts when setting up a newly built or restarting aquaponics system. Cycling with fish generally takes 4-6 weeks. This time frame is dependent on the water temperature, which is ideally 75° - 80 ° F. The temperature outside this range will take longer to cycle because the bacteria will be slow to eat and reproduce. However, you can speed up the cycling process by using other cycling methods.
Maintaining an aquaponics system can be challenging and stressful when you don't have enough experience and knowledge. So it's vital to have a clear picture of what is going on in your aquaponics system to know what you can do to maintain the right conditions for your system to work.
Learning about aquaponics can be challenging at times, but many free resources are available online if you are interested in learning. You can also read our article, The Ultimate Aquaponics Beginner's Guide, to learn on starting your own aquaponics garden.