Aquaponics refers to any system that combines conventional aquaculture with hydroponics in a symbiotic environment. The aquaponics system was started at Sacred groves to realise the ‘waste is food’ concept. To achieve a way in which the recycled grey water can be used for rearing fishes and using the same water rich in nutrition for growing food. Thus attempt to close the loop of waste and food cycle in a systematic manner.

Components of the aquaponics system:

1. Rearing tank: The tanks for raising and feeding the fish.

2. Bio-filter: An arrangement where suspended algae are cleaned and the nitrification bacteria can grow and convert ammonia into nitrates by aerating it, which are usable by the plants.

3. Hydroponics subsystem: The system where plants are grown in water rich in nutrients provided by fish poop.

4. Sump: The lowest point in the system where the water flows to and from which it is pumped back to the rearing tanks.

How does the aquaponics system work?

• The fishes are fed regularly on a daily basis.
• The excreta of fishes are rich in nutrients and it especially provides a good amount of ammonia. But plants cannot absorb ammonia.
• The water from the rearing tank is circulated through the bio filter system.
• The bio-filter removes the algae and aerates the water to break ammonia into nitrates and nitrites.
• Then water is supplied to the hydroponics system.
• The grow bed of plants in hydroponics system is made of small broken tile pieces, spandex ceramic or any other porous material.
• It provides a firm base for plants to stand straight and it also acts as substrate for bacteria (generally nitrogen fixing bacteria) to thrive.
• The bacteria break down the nutrients to a form which plants can absorb.
• Then water is directed back to the rearing tank.

To ensure plants don’t suffer from deficiencies, maintain optimum water pH (6-7) and feed the fish a balanced and complete diet, and use the feed rate ratio to balance the amount of fish feed to plants.As of now we produce some basil, spinach and lettuce in our aquaponics system. The volume of water in the rearing tank is enough grow more plants and we are working towards that direction.

Other than the vision we need to achieve, the aquaponics offers various advantages over the conventional cultivation practice.

Advantages of aquaponics over soil crop production:

• Fertilizer: In soil-less culture, nutrients are dissolved in a solution that is delivered directly to the plants, and can be tailored specifically to plants’ needs. This saves a lot of money as fertilizer is expensive. This tailored management of nutrients can improve productivity and enhance the quality of products.

• Water use: Aquaponics uses only about 10% of the water needed to grow the same plant in soil. Soil-less cultivation has great potential to allow production where water is scarce/expensive.

• Utilization of non-arable land: Aquaponics can be used in urban/peri-urban areas that cannot support traditional soil agriculture.

• Productivity and Yield: Aquaponics techniques can be more productive than soil, because it allows the farmer to monitor, maintain, and adjust the growing conditions for the plants, ensuring optimal real-time nutrient balances, water delivery, pH and temperature. There is no competition with weeds!

• Reduced workload: Soil-less culture does not require ploughing, tilling, mulching or weeding. Products do not need extensive cleaning to remove soil contamination.

• Sustainable monoculture: It is possible to grow the same crops year after year using aquaponics. Soil-based monocultures are difficult because over time the soil loses its fertility and pests and diseases increase.

• Although aquaponics is more expensive than hydroponics because the plant units need to be supported by aquaculture installations, and if any one part of the system fails, the entire system can collapse, it benefits the farmer in the long run.

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