Aquaponics is, quite simply, a combination of aquaculture and hydroponics. It is a complete food production method that is organic and does not use pesticides. Aquaculture involves the growing 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 aquaponic systems 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 bacteria in the grow beds. The plants are fed nutrient-rich water 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. Read more about the benefits of aquaponics.
How does Aquaponics work?
For aquaponics to work at all requires the presence of a living microbial community largely consisting of beneficial bacteria. It does not involve soil. 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.
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 (Recirculating Aquatic Systems). They include;
- 90% reduction in water requirements compared to soil-based production.
- Elimination of many soil borne pests and diseases
- Higher planting densities possible particularly with vertical growing methods making maximum use of space.
- 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 buildings 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. The disadvantages are largely eliminated if production intensity is kept at a more sustainable level.. Every year new and exciting possibilities are being discovered.
Basic Types of Aquaponics Systems
Aquaponic farmers have adopted several different designs of hydroponic systems.
Media-based Grow Beds
The plants are grown in a 30 cm. deep bed of media that is repeatedly flooded and drained with fish water. This ensures a continuous and steady supply of fish waste from the fish tank. This is steadily broken down by bacteria into plant feed. All of the plant food actually originates from the fish food.
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.
Nutrient Film Transfer (NFT)
A series of pipes and troughs supply the nutrient-rich water from the fish tank to the plants.These are usually held in small pots containing an inert material to provide physical support for the growing plants. 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. Good back up pumping arrangements can become crucial.
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. Excess solid accumulation and excessive root development are the two most common threats to the long term operation of such a system.
The drastic reduction in the need for a flow of fresh water has presented the opportunity for much greater control of the fishes 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. Heating does require the use of a building and efficient insulation. A low cost poly tunnel or green house is a very viable solution.
What plants and fish to grow
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 to fish. Plants that do particularly well in an aquaponic system include;
- Leafy greens such as lettuce
- Tomatoes, peppers and cucumbers
- Herbs such as basil, coriander, parsley
- Flowering plants like chrysan
- Fruit such as strawberries
Site Selection Freedom
One of the great things about aquaponic systems is that the operator can be in complete control of the entire growing process. Unlike more conventional methods of food production aquaponics does not need any specific soil conditions ( or any soil at all). Neither does it need copious amounts of fresh water. The overriding advantage is that this type of food production can be sited almost anywhere. With the provision of lighting it can even be installed inside redundant buildings. Urbans farms and roof top gardening schemes are here to stay.
The production of local fresh food in the heart of our cities is a really exciting prospect.
Scalability of Aquaponic Systems
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, of course, 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.
After feed costs those involved with pumping and heating are usually the most important. Of the two it used to be thought that heating was the highest. Practical experience has shown that, with adequate insulation, and a low influx of fresh water, heating costs can be remarkably low. Pumping costs need careful consideration and every effort should be made to keep the head height to an absolute minimum. Pumps need to run 24/7 and really are the heart of the system. Care should also be taken minimise frictional loses as the water passes through the connecting pipes. Pipe work should be of adequate diameter, as short as possible and accessible for routine cleaning. Conditions for bacterial growth are ideal within the pipework.
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?