To avoid chemical-laden vegetables in their diet, urban farmers are opting for another method of organic farming – aquaponics. The method is a marriage of aquaculture and hydroponics (soil-less growing of plants) – fish are reared in tanks, their wastewater provides food for growing plants, and the plants act as a natural filter for the water which the fish live in. So fish and plants grow together in one integrated system.
One aquaponics enthusiast is aircraft maintenance training instructor Affnan Ramli. For the past eight years, his home has been an experimenting ground for the green farming method; he hopes to develop a system that suits Malaysian homes and environment.
When he started out, aquaponics was unheard of here although it was already gaining popularity elsewhere. So he pretty much learnt everything himself. Now, he is so well-versed in the subject that he is sought after for advice by other enthusiasts in the small but growing local aquaponics community.
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The chemical-free nature of this green farming method was what caught the aircraft engineer’s attention. While hydroponic farming relies on nutrients made from a concoction of chemicals, salts and trace elements, aquaponics on the other hand needs no chemical input as nutrients for the plants come from fish waste. Ammonia in the waste is converted by bacteria into nitrates that are food for plants.
In hydroponic systems, the water needs to be discharged periodically as salts and chemicals build up in the water which becomes toxic to the plants. In aquaponics, little water is needed as it is recycled.
“Water is added only if it is lost through evaporation. The water in the fish tank is clear as it is filtered by the growing vegetation. There is no odour and the fish I rear do not have any bad taste or smell,” says Affnan, 54.
Of course, nothing can beat farming in soil, but it requires large areas and plenty of water. Aquaponics is said to require only a quarter of the size of a farm to produce the same amount of vegetables. Plus you get a double crop – fish and greens.
Affnan believes aquaponics is the perfect farming method for urban areas since it requires minimal space. At his home in Bukit Subang in Shah Alam, he has built aquaponics systems to demonstrate that they can fit into a typical 6.1m x 21.3m (20ft x 70ft) link house. The most basic system consisting of a 1m x 1.5m fish tank and a smaller planting box above it is compact enough to fit into an apartment balcony.
It’s a modular system, so one can combine two or three sets to get a bigger set-up, as displayed in his backyard. There, he has put together three fish tanks in which he rears tilapia, catfish, lampang and jade perch. Stacked above the fish tanks are four smaller planter boxes holding potted chillies, rosemary, eggplant, mint, lemongrass, chives, pandan, turmeric and a herb, sambong nyawa. And that’s the beauty of aquaponics – both fish and farm share the same space.
There are different approaches to aquaponics. In the raft-based growing system, plants are placed in holes in a foam raft that floats in a channel or tank filled with fish effluent water. This method, however, is suitable only for plants where the roots can be submerged all the time. It is most appropriate for growing salad greens and other fast-growing, relatively low-nutrient plants.
Another method has the plants growing in planting media such as gravel, coir and clay pellets. The grow bed also functions as a filter and living space for bacteria which are essential for breaking down elements in the water into a form which the plants can absorb and use.
The watering system here is known as the flood and drain method. In this method, water from the fish tank is pumped up to flood the planter box. Once it reaches the desired level, it drains back to the pond through a siphon that is placed to the correct height. This gives oxygen to the plant roots and moisture to the bacteria that converts ammonia to nitrates in the wastewater.
Affnan chose to work with this system as it is suitable for most types of vegetables. Initially, he had problems controlling the water level. But he persevered and after some eight months of tinkering with the system, he got it working properly and reliably with just a slight modification to the siphon – he replaced the cylindrical tube with a funnelled one. Because of that, the global aquaponics community now calls that design the Affnan siphon.
He used to sell basic aquaponics sets to enthusiasts but has since stopped. “It’s better if they DIY … they will understand better how the system works. If I sell the set, people expect it to work perfectly and if it doesn’t, they just give up. It is better for people to do their own research, learn, evaluate, then they’ll know what they’re doing,” says Affnan.
He says system failures are usually due to poor understanding and a lack of information. Common problems encountered are pump failure and a clogged siphon. He says both must be cleaned periodically. One must also grow suitable plants. A new aquaponics system must have time to mature – that is, for the nutrients to build up. If one immediately grows nutrient-demanding plants such as tomato and chillies, it will fail. One should first start with less demanding low-nutrient plants such as mint, basil and kangkung. Sometimes, the plants may not thrive due to certain nutrient deficiencies, so supplements such as iron or Epsom salt (to promote chlorophyll growth) can be added.
Affnan has not had to buy fish for a long time but he has yet to grow enough greens to fully feed his family. “Most of the time, I’m experimenting. I’m trying to make it easier for everybody, by developing an aquaponic system that works best here. I’d want to make that system available to everyone so they can try out this method of planting.”
All urban farmers will certainly look forward to that day.