Our latest issue features a profile of creative Vancouverite Shaun Mavronicolas and his home-scaled solution to putting food on the table. Here's an excerpt, plus a tour of Mavronicolas' DIY setup and the essential components that make aquaponics work.
The notion of cultivating fish and plants together is not new. Over the centuries, many cultures have developed and combined aquatic and terrestrial food production systems. The Aztecs of Mesoamerica produced staple foods, water plants and fish using chinampas, a series of artificial islands and dredged channels. Across Asia, the Food and Agriculture Organization of the United Nations has documented a host of time-tested systems, from Chinese farms raising grass-grazing fish and Indian duck-fertilized fishponds, to freshwater prawns and fish grown in the flooded rice fields of Indonesia and coastal Vietnam. These traditional systems take advantage of natural nutrient cycles between flora and fauna to generate bountiful yields of produce and protein.
Modern-day aquaponics, which combines the techniques of aquaculture and hydroponics, generally opt for a higher-tech approach to produce high yields in small spaces. Mavronicolas’ crops rested on a bed of expanded clay aggregate – airy terracotta spheres that permitted the roots access to both oxygen and nutrient-rich waters. Next to long trusses of tomato vines and heads of bushy lettuces, a school of tilapia swam inside a 1,900-litre tank. Overhead, full-spectrum fluorescent banks on timers (a necessity for growing year-round in Canada) lavished basil shrubs with light.
A Look at Aquaponics Hardware
Framing and construction of the flood-and-drain grow beds.
A fully assembled bed, ready for hydroton (expanded clay) grow medium.
Two kilowatt inline fish tank heater, mostly used during winter.
Young Fairytale eggplants, beans and basil growing in hydroton media.
Koi pond drum filter, the primary mechanical filtration for the RAS (recirculating aquaculture system).
DIY radial flow filter for reclaiming water from flushing the drum filter.
Recipe for Successful Aquaponics
Aquaponics marries aquaculture (growing aquatic organisms) and hydroponics (growing plants without soil) into an integrated food production system.
Aquaponics may seem like a simple setup wherein plants and fish coexist in neat, perfect harmony. But like any ecosystem, the key drivers are invisible: colonies of nitrosomonas bacteria convert ammonia excreted by fish into nitrite, while nitrobacter bacteria convert the toxic substance into nitrates to be taken up by plants. These microbes are present in the air and will populate the biofilter in the system as soon as ammonia is introduced. But patience is required – nitrifying bacteria grow slowly and the entire cycling process for a new aquaponics system can take up to six weeks.
Nitrogen-loving plants that grow leaves (such as lettuces and herbs like basil) and/or bear fruits (tomatoes, cucumbers, melons) thrive in well-stocked systems. Root vegetables and tubers such as carrots and potatoes are less suitable due to the coarse growing medium and the constant flooding of roots.
Suitable edible species will tolerate close living conditions and are fast growing. Tilapia is a hardy and popular choice – omnivorous, unfussy about water quality and able to grow from fry to plate-sized in nine to 12 months – ideal for those interested in growing a steady source of animal protein. Another good option is rainbow trout, which does well in cold, oxygen-rich waters, but requires feed derived from fishmeal. For smaller systems or to produce only vegetables, goldfish and koi are easy to keep and tranquil to watch, plus they can be sold at a profit to the aquarium trade.
Aquaponics systems can vary greatly in size, complexity and diversity, and should be tailored to local space and lighting conditions. One key question seems to be: one large system or several small ones? A system with a 1,900-litre tank may be cheaper to operate and easier to design, but three smaller tanks of equivalent volume offer redundancy and may be easier to manage should things go awry.
Additional beginner resources
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