Growing up, Pruthvi Ravindra spent his holidays at his family’s three-acre farm near Davanagere in Karnataka. “In the holidays between Class XII and college, I would visit the farm every day as my father was setting up an areca nut plantation. That’s when my interest in farming and gardening kicked in," says Ravindra, now 37. A mechanical engineer with Caterpillar, Ravindra revived his interest 18 months ago by setting up an aquaponics system on the 21 sq. ft balcony of his house in Bengaluru’s Kundalahalli.

It’s all organic

He started with regular pot plants and a few leafy greens and vegetables. But soon, Ravindra was intrigued by what he had read about aquaponics online. Aquaponics is a form of soilless cultivation, where the plants grow on water that comes from fish tanks. “It consumes 90% less water than soil cultivation and doesn’t use any chemical fertilizers. Unlike hydroponics, where one has to add certain chemicals to the water, in this system, it’s the fish waste that is converted into nitrates and fed to the plants," he explains.

Ravindra, who was working with GE at the time and had shared his interest in gardening with five colleagues, would often exchange tips and ideas with them. “But they weren’t convinced about the aquaponics system, so I decided to set up a prototype at home," he adds.

Last June, he bought a plastic drum, trays and pipes as well as tilapia fish from a fishery to get started. “The first one-and-a-half months were a complete failure. I was still figuring out how it works, when and how much to feed the fish," he admits. Three months later, his efforts were rewarded. “The palak leaves were the size of my palm; the basil plants were 4ft tall and there were abundant tomato and chillies growing," says Ravindra, who also put in a vertical PVC pipe fitted with coir to grow lettuce.

When he showed videos of his home garden to his then colleagues, they were all inspired. They collaborated and set up a larger aquaponics system (2.5ft by 5ft in size and 4ft height) on the terrace of one of his friend’s homes in Ramamurthy Nagar.

“The idea is to grow enough for all our five families. At the moment, we are growing tomatoes, celery, chillies, leafy greens and herbs," Ravindra says. They have developed a three-tier system with the fish tank forming the bottom tier, and the first and second tier comprising beds on which they grow 10-16 plants each.

Water is pumped through a tray filled with gravel and LECA (lightweight expanded clay aggregate or clay pellets) and the bacteria convert the ammonia (produced as fish waste) into nitrates that can be absorbed by the plants. The water then falls back into the fish tank, ensuring that it gets recycled.

Building from scratch

There are companies that sell aquaponics equipment and can also set up the system, but Ravindra found them overpriced. “One place was charging 25,000 just to put up the structure. Being mechanical engineers, we decided to come up with the designs ourselves. We’d spend weekends at each other’s homes working on spreadsheets and drawings."

When they went looking for welders to build the structure, they were disappointed to find that most were charging exorbitant rates or needed three-four weeks’ time to finish the work. “Since three of us had worked as marine engineers in the past, we decided to do the work ourselves. Once the designs were ready, it took us a couple of days to build it," says Ravindra. They spent about 10,000 for the system they put up on his friend’s terrace and 6,000 on a second prototype they developed for an indoor use.

The biggest challenge was making time for the work that went into designing and building the aquaponics systems.

Ravindra, whose shift starts at 7.30am and can go on till late in the evening, only had weekends to figure it all out. “We’d take turns meeting at each other’s homes. Sometimes, we had to meet at malls or public spaces when there were guests at home or because it was more central. We have even carried our laptops with us and met at a park a few times," he says.

They formed a WhatsApp group where they’d exchange ideas or post interesting videos or articles they found online. Apart from watching “thousands of YouTube videos", the group visited a couple of aquaponics farms in and around Bengaluru and went to an agritech expo to gather contacts to source equipment.

With most of the hard work behind them, Ravindra is now reaping the benefits of having chemical-free produce available at all times.

“If you buy hydroponically grown vegetables in the market, they cost two to three times more. Sometimes, we have so much lettuce or basil that I distribute it at work," says Ravindra.

Urban farmers explores the lives of professionals who experiment with farming at home.

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