Aquaponics is, quite simply, a combination of aquaculture and hydroponics. Aquaculture involves the rearing of aquatic animals, usually fish. Hydroponics is the soilless culture of plants. Both techniques have become increasing popular as a means of feeding the world’s ever-expanding population.
Aquaponics = Aquaculture + Hydroponics
The greatest advantage of aquaponics is that the fish and plants co-exist in a mutually beneficial relationship. The fish have their waste products broken down and purified by the plant beds. The plants are fed nutrients that result from this breakdown. In this way a more balanced, sustainable and staple environment is maintained. The benefits of aquaculture and hydroponics are retained and the disadvantages reduced.
How does Aquaponics work?
For aquaponics to work at all requires the presence of a living microbial community. This community lives predominantly on the surfaces of the plant growing medium and plays a huge part in the Nitrogen Cycle.
Aquaponics therefore involves the integration of three living ecosystems, namely the plants, the fish and the bio filter.
The Pro’s ……. and the cons
Over the last few decades aquaculture has expanded rapidly to become and increasingly important source of fish. As a result of our greed, and poor management, our fisheries have sadly declined. Recirculating aquaculture systems (RAS) represents an exciting and developing sector of aquaculture. RAS utilise a range of water treatment processes to enable the effluent from the fish rearing tanks to be purified and returned. This not only greasy reduces the water requirements but allows much greater control of the fish environment.
- Over 90% reduction in water requirments
- Elimination of many pond borne parasites and diseases
- Much faster growth rates
- Year-round production
- Year-round spawning potential
- Greater protection from predators
- Ability to site farms close to local markets
- Greater stocking rates possible
- Higher energy requirements
- High reliance on power supply
- Automatic fail-safe standby arrangements often required
- High capital investment in novel water treatment equipment
Hydroponics has shown a similar rise in popularity and is a well-established method of plant production. The advantages it enjoys are remarkably similar to those of RAS. They include;
- 90% reduction in water requirements compared to soli-based production.
- Elimination of many soil borne pests and diseases
- Higher planting densities possible particularly with vertical growing methods
- Much faster growth rates
- Year-round production possible with additional heating, ventilation and lighting systems
- Ability to site farms almost anywhere including basements, gardens, greenhouses and rooftops. Disused building in the urban environment make great locations for community projects
- Greater protection from predators
Disadvantages of hydroponics;
- High energy requirements for high production rates
- Reliance on artificial nutrient provision at high expense
- High capital investment in environmental control equipment.
It is clear from the above that both systems have much in common. By combining the two aquaponics retains the advantages. By keeping production intensity at a more sustainable level the disadvantages are largely eliminated or greatly reduced. Every year new and exciting possibilities are being discovered.
Basic Types of Aquaponics Systems
Aquaponic farmers have adopted several different hydroponic systems.
- Media Grow Beds
These consist of a 30 cm. deep bed of media that is repeatedly flooded and drained with fish water.
2. Deep Water Culture (DWC)
The plants are placed at regular intervals into a floating raft . The roots simply grow down into the fish water to obtain their nutrients. A separate system of removing suspended sold is usually required otherwise there may be an excessive buildup of waste within the tanks. It is, nevertheless, a popular system for large, commercial farms. It is perhaps less suited to growing plants with extensive root systems that are needed to support larger plants.
3. Nutrient Film Transfer (NFT)
The plants are supplied with all the nutrients they require through a series of pipes and troughs. Systems are light and perfect adapted to vertical growing. On the down side they also cannot support heavy plants and the nutrient film is more vulnerable to temperature fluctuations.
Generally speaking the media filled grow beds represent the best choice for small scale aquaponic systems. They provide both a means of suspended solids and ammonia removal and the best support for a wide range of plants.
What to grow
The drastic reduction in the need for a flow of fresh water has presented the opportunity for much greater control of the fish environment. It now becomes a practical possibility to heat the water and gain faster growth rates and all year round production. Indoor farming is now a rapidly growing sector offering numerous advantages over traditional farming methods.
Both fish, plants and biofilter share a common environment. As a direct consequence the pH does need to be favourable to all and around neutral. It is best to avoid plants that have a personal preference for strongly acidic or alkaline conditions.
Fish selection is partly a personal one and partly dependent upon water temperature. Disease-free fingerling supply can often limit fish selection. Choice really boils down to whether or not you want something to eat, or something to just admire. Choice however will normally fall within one of the following three groups;
- Coldwater edible fish such as trout and charr
- Warmwater edible fish such as tilapia, carp and catfish
- Warm water ornamental fish such as koi and goldfish
There tends to be a much larger choice of plants to grow. Availability of seed does not limit choice in the same way as availability go fish. Plants that do particularly well in an aquaponic system include;
- Leafy greens such as lettuce
- Tomatoes, peppers and cucumbers
One of the great features of aquaponics is that it is eminently scalable. It can be as tiny as a single Siamese Fighting Fish in a few litres of water on your window cill growing a few herbs to large commercial greenhouse system covering tens of thousands of square metres. It is perfectly feasible to raise all of a family’s vegetable needs, including flowers and herbs, in a modest sized garden. There is the added bonus of a regular supply of fish.
When we consider ‘What is Aquaponics’ we should not underestimate the power it has to educate. Fish add a great deal of colour , movement and interest to the growing of plants. Children and adults alike simply love to see them. The systems are safe, and perfectly child-friendly. What better way is there of getting children to ‘eat their greens’ than to get them involved in their production? Of course, all that boring ‘scientific stuff’ about animal/plant relationships is also perfectly demonstrated. Find out more about aquaponics for schools.
Profitability is certainly not some kind of utopian dream. It is now genuinely achievable with over 60% of indoor aquaponic farms in the USA now turning a profit. Aquaponics achieved twice the revenue of hydroponics. The future of aquaponics looks incredibly bright for many years to come.
Our advice for anyone thinking of embarking on this exciting new adventure has always been the same. Start small and expand what works for you. Remember aquaponics is eminently scalable.
So what are you waiting for?