Aquaponics: Components, Methods, Benefits & Drawbacks

Aquaponics is a combination of aquaculture and hydroponics, which involves growing fish and other aquatic animals and growing plants without soil. Aquatic plants consume animal waste and clean the water for fish in return. Along with the fish and their excretion, microbes play an important role in the plants’ nutrition. In root spaces, these microbes break down fish wastes and solids into substances that help plants grow. Eventually, aquaculture and gardening form a perfect partnership.

Aquaponics presents a big scope for sustainable organic crop production, aquaculture and water consumption. Instead of throwing away the fish waste in the ocean, the waste is recycled and used for plant growth. Closed-loop recirculation of water reduces resource consumption.

Let us now try to understand in detail the components of aquaponics.

Aquaponics – Living Components

An aquaponics system consists of three main components: Plants, fish, and bacteria.

Plants

The whole purpose of this aquaponics is to grow plants in a sustainable form. As a natural filter for the water, plants absorb nitrates, detoxifying the water and recirculating it.

Green leafy vegetables such as cabbage, lettuce, spinach, chives, etc., that do best in low-nutrient media can also be grown along with salad plants like cucumber, tomatoes, capsicum, onions, snow pea, etc.

Fish

The excretory waste from the fishes provides nutrients required for plant growth in aquaponics. When selecting fishes for aquaculture, a number of factors need to be taken into account as they will live in a tank environment and have to withstand high population densities. The best fish for home or commercial aquaculture is Tilapia, as they can grow rapidly and are high population density living fish. Other suitable fish are catfish, trout, largemouth bass and perch.

Bacteria

Another vital component of aquaponics is the nitrifying bacteria, which helps in increasing the nitrogen content of aquaculture through a process known as nitrification. As bacteria convert the waste of fish into nutrients, they play a vital role in the cycle. The plants absorb these nutrients through a process called nitrification.

Ammonia is released into the water through excreta and gills of fish; it has to be removed from the water as its higher concentration can retard the growth of plants. So, ammonia has to be converted into nitrates for absorption in plants by two types of bacteria: Nitrosomonas, which converts ammonia into nitrite, and Nitrobacter, which converts nitrites into nitrates. Once nitrate is formed, it can be absorbed by the plants.

Parts of Aquaponics System

1. Rearing tank: The tank used for raising and feeding of fishes.
2. Settling Basin: The tank is used to hold uneaten food as well as settle fine particles.
3. Biofilter: A place where the nitrification process can occur, converting ammonia into nitrates that the plants can use.
4. Sump: It is present in the lower point in the aquaponics set up to provide water to and fro between the tanks.

Methods of Aquaponics

1. Deep Water Culture (DWC), or Raft Based Growing: It is the most efficient method for large scale commercial production because, in this technique, the raft covers a huge amount of space. A foam raft floats in a waterway filled with fish waste. The fish waste is filtered out to remove solid wastes. Plants are planted on a raft, and their roots are suspended in the water from the holes created at the base. Once the plants are harvested, the raft can be reused for another cycle of planting. Plants that can be harvested in one season, grows rapidly and has low nutrient requirement like green salads are best suited for this method.
2. Media-Based Aquaponics: The media-based method is suitable for growing plants in a large container filled with perlite, clay pellets, gravel or shale media. This method requires minimal components as filtering of solid wastes does not require an extra filter as it is mechanically broken down throughout the media. Additionally, the reduction of various nitrates is made by the biological method. This system has low plant product output and thus, cannot be used commercially. However, due to its cost-effectiveness as being less expensive and a relatively easy setup, this kind of aquaponics can be developed  his kind of aquaponics is suitable for home gardening to grow a variety of crops to grow a variety of crops. Large fruiting plants, in particular, thrive better than leafy greens, herbs, and other types, as constant media support can be provided to the plants.
   
3. Nutrient Film Technique (NFT): NFT systems are quite common in hydroponics but is used in aquaponics. In this system, the water moves through a narrow pipe, which improves the nutrient and oxygen supply to plants. This water requires an extra-biological filter, as the system is not exposed to air. Fish organic farming is not used, as the solid waste can lead to clogging in the system comprising of thin pipes. Small green leafy plants with a small root system and strawberries can be cultivated through this system.
   
4. Vertical Aquaponics: Vertical aquaponics is the best-suited method for cultivating a large number of plants in a small space. Vertical tower systems like Aquatica consist of plants stacked atop each other. Water is allowed to flow through wicking material at the top of the tower so that the roots of the plants can absorb water and nutrients. After that, the water directly falls into a fish tank or a trough. Leafy greens, strawberries, and other crops are most suited to be grown by this technique.

Benefits of Aquaponics

1. Aquaponics is primarily used to produce sustainable food.
2. It does not require soil, so it is not susceptible to diseases transmitted through the soil.
3. It doesn’t require the use of chemical pesticides or fertilizers.
4. Increasing yields and improving quality are key characteristics of aquaponics.
5. Aquaponics improves biosecurity and reduces the risk of contamination from the outside.
6. Aquaponics allows for better control of the production process (since it is easier to manage than soil) and lower losses.
7. It can be applied to non-arable lands, such as deserts, degraded soil, or salty, sandy islands.
8. Aquaponics produces little waste since it imitates the circular approach of nature.
9. Aquaponics requires no special tools and can be operated by people of all ages and genders.
10. With aquaponics, landless and impoverished households can secure quality food and income.
11. With aquaponics, you can produce a fish protein which is great for many people.
12. There are lakes, ponds, rivers, and waterways throughout the planet, all of which can be mimicked with aquaponics.
13. Aquaponics provides both protein (derived from the fish) and vegetables, considered nutritionally adequate.

Drawbacks of Aquaponics

1. It is relatively more expensive.
2. It requires extensive knowledge of the plants that can be supported in a given type of system. All plants are not supported by this technique.
3. In the case of aquaculture, a thorough knowledge system is required to maintain an appropriate pH, temperature, substrate to sustain both fish and plant systems together.
4. The cost of maintenance and operation is high as it requires the usage of multiple filters.
5. Improper management of the system can rapidly result in it collapsing.
6. It requires regular management for effective functioning.
7. It has a high electricity consumption requirement.
8. Regular purchases of fish food are necessary.
9. The setup can be done only by professionals.

Summary

Aquaponics combines aquaculture and hydroponics for creating sustainable food production. Plants take up the excretory waste released by the fishes broken up by the nitrifying bacteria, which breaks the ammonia into nitrates that the plants have picked up, clearing the water. Various plants like cucumber, cabbage, tomatoes, basil etc., can be grown, and the best fish for aquaponics is Tilapia, as it can easily grow in densely populated tanks. Aquaponics is environmentally friendly as it does not require any chemical fertilizers as there is no soil requirement. This technique is best suitable for the desert, semi-arid areas and requires cheap labour. On the other hand, aquaponics is a costly process and requires daily monitoring of pH, temperature, and the substrate of the tanks.

Frequently Asked Questions (FAQs) on Aquaponics

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