Aquaponics has proven more popular with gardeners than with any other group of users. This is hardly surprising when we look at the extensive list of strengths afforded by this method of growing plants. The ease of food production, high rate of productivity and the inherent versatility of the system will ensure that this fantastic growing system is here to stay.
For those of you who are not familiar with this method growing plants it can simply be explained as the combination of aquaculture and hydroponics. Aquaculture is the raising of aquatic creatures and hydroponics is the soilless culture of plants. Follow this link to find out more about what is aquaponics?
First of all, let’s discover the benefits that aquaponics has to offer.
i) 90% less water
All the water used is retained in water-tight containers and is prevented from draining away naturally. Only that lost through evaporation and transpiration needs to be replaced. Conventional gardening typically uses ten times as much water as aquaponics. It’s not surprising that aquaponics is so popular in the drier regions of the world such as Australia. In the UK this water efficiency allows us to utilise municipal water supplies and site aquaponics systems in gardens, redundant buildings, rooftops and many other urban environments.
The fish also require just a fraction of the water normally used in aquaculture. Recirculating Aquatic Systems (RSA) typically use less than 5% of that required by traditional fish farming techniques. The grow beds remove suspended solids and ammonia and air pumps replenish the oxygen used, not only by the fish, but also by the filter bacteria and the plants at night.
I would still recommend that a slow, continuous water change is carried out to help control other water parameters such as dissolved solids and alkalinity. This is cheap and easy to achieve by including a simple continuous drip with excess water allowed to escape via an overflow in the sump tank.
ii) No Digging
The plants are grown in lightweight media and the nutrients supplied via a constant supply of water. Furthermore there is no compaction and digging is a thing of the past. This not only saves you from back ache but also allows the natural development of microorganisms.
iii) No Watering
The plants always have access to water and nutrients. Provided evaporation losses are made up there is consequently no requirement for regular watering. Certainly a simple ball-valve could be used to automate any top up required. Over or under watering is probably he biggest cause of plant failure for most gardeners.
iv) Very Little Weeding
I wouldn’t say that there is no weeding but any weeds that do appear are very easily dealt with. As a result it’s almost a joy! The top layer of media is usually kept dry further restricting the growth of unwanted weeds and algae.
v) No soil borne pests and diseases
Lack of soil reduces the presence of both plant and fish pests and diseases. The life cycle of many pests are naturally broken in the absence of soil. Therefore there is little need to resort to pesticides.
The absence of other pond creatures will also help break the lifecycle of some important fish diseases. Lack of snails, for instance, will remove the threat of the blood fluke, Sanguinicola sp. that rely of pond snails as an intermediate host in their lifecycle.
vi) No messy soil
Often we gardeners quite like to get our hands dirty. There are times however, when we, and the kids, would rather be kept clean Clean conditions are specially welcome when growing and harvesting salad crops on a daily basis.
vii) No bending
It is often possible to have our grow beds at bench height. This makes gardening a real comfort. For many people, in many situations, this is often essential. It also helps to keep the plants away from ground level pests such as slugs, snails and even rabbits.
viii) Greater productivity
The constant supply of water and nutrients from the fish waste encourages optimal plant growth. Closer spacing of plants is perfectly possible thus maximising productivity and use of space. Growth rates are also generally greater and hence allows us to produce more plants in a given area.
ix) Great for polytunnels and greenhouses
Aquaponics lends itself remarkably well to utilising polytunnels and greenhouses. Both the fish and the plants , not to mention the gardeners, greatly appreciate the higher temperatures and protection from the great British weather.
x) Fully organic
This is becoming more and more important to more and more people. Aquaponic systems do not involve nearly so many pesticides and artificial fertilisers. These chemicals can often be completely eliminated. They are not necessary and besides, could have a catastrophic affect on the health of the fish. Fish waste is a very organic nutrient source for plants
xi) Excellent wheelchair access
Aquaponic systems should not restrict disabled gardeners in any way. Easy access to the plants is a benefit for everyone. Growbeds can be positioned at many different heights facilitating access for wheelchair users in particular. The fish tank is also much smaller and more accessible than a typical pond.
xii) Locate almost anywhere
Aquaponic systems are not dependent upon local soil conditions as none is required. Equally, water availability is less important. Simple lighting kits can easily enhance light levels if required. Popular locations for aquaponic systems include rooftops, basements and many disused buildings.
Finally, I’ve saved the most important strength ’til last. Aquaponics is nothing if not versatile. The range of fish and plants suitable for aquaponics is extensive and can be chosen according to individual preferences. Control over water temperatures and quality allows us to grow non-native species that would otherwise be impossible. There are few plants that cannot be grown in one type of aquaponics system or another. The only limitation is the pH must be in the 6-8 range for the health of the fish. Deep Water Culture (DWC) rafts are ideal for commercial production of lettuce and herbs. Media based systems are able to provide greater root support for larger plants like tomatoes, herbs and peppers. Nutrient Film Techniques (NFT) are popular for the production of strawberries and integrated vertical growing systems that maximise production per square meter.
With regards to choice of fish, Tilapia are often a popular choice provided warm water can be provided all year.
Systems can be entirely functional or geared more to display. The choice is yours. Fish don’t have to be eaten and neither do the plants. Ornamental fish like goldfish and koi will always be a popular choice for many. Without the pressure to produce many types of garden pond can benefit from the low maintenance requirements, and cost efficiency, of an aquaponic filtration system.
It wouldn’t be fair however, not to discuss potential weaknesses and pitfalls. None of these are insurmountable. Indeed, many people would see some of the following as strengths.
i) Fish keeping skills required.
Don’t allow yourself to be put off if you have never kept fish before. Fish farming can be as simple as you like. Goldfish are very hardy and easy to keep. They are cheap and readily available. It makes very little difference to the plants whether you keep goldfish or trout. They both produce ammonia and fish poo from the fish food and supply your plants with all the nutrition they need.
ii) Need to balance fish and plant requirements.
Maintaining a natural balance is the name of the game here. Mother Nature tends to balance things out. Available food supply often limits the growth of the fish, plants and filter bacteria. How much food is eaten, how much ammonia is consequently produced and how rapidly this ammonia is broken down are all primarily affected by water temperature. By and large we do not have to interfere. There are limits however. We need to recognise these limits and know how to overcome them. The behaviour of the fish and the growth of the plants can tell us a lot about these limits. Without this experience we need to carry out routine monitoring of water quality. Inexpensive kits are widely available and cover most potential eventualities.
iii) Long term commitment.
All biofilters need time to mature. This can stretch to a few months under some conditions. However, there is little to do over this period and maturation will generally take care of itself. Keep feed levels low by operating well within the carrying capacity of your system. Once matured everything becomes well balanced.
i) Excellent disabled access.
Engage with adults and children of all abilities. Wheel chair access is easy to incorporate. While the reduced need to bend is also very welcome for most of us.
ii) Use of redundant buildings
The addition of lighting, heating and ventilation systems has the potential to allow the use of many redundant buildings . Often these facilities are standing idle in derelict urban environments
iii) Year round production
Growing plants and fish all year round is a real possibility and almost certainly offsets the additional costs of lighting, heating and ventilation involved. Even if you do not want to run to the expense of lighting your entire grow bed much can be gained from growing a few leafy greens in the middle of winter.
Finally, it is important to recognise that there are some potential threats inherent with aquaponics systems. As a result, careful system design, and a bit of preparation, usually turns a potential catastrophe into just a minor inconvenience.
i) Power failure
Fish depend upon the continuous operation of pumps to provide oxygen and clean water. As a result it is vital to overcome the threat of power failure by using an air pump as an additional source of aeration and have a spare water pump always available. Certainly keep fish stocking densities as low as possible. This will maximise survival times for the fish in the event of a power failure. Finally, there are more and more opportunities today to mitigate this threat by developing smart monitoring systems over the internet.
This is always a threat with any living creatures. In a farming situation with high densities of livestock this becomes even more important. Organic plant pest control techniques are essential in order to safeguard the health of the fish. Above all else, I must emphasis the importance of finding a good reliable source of disease-free fish. Breeding your own stock has many advantages but not always practical on a small scale. Effective quarantine facilities and a biosecurity plan have become a necessity over the last few years rather than something ‘nice to have’.
In conclusion, these are my personal recommendations to ensure success with any aquaponic gardening system.
- Start off small. Give your biofilter time to mature. Fish can grow remarkably quickly when operating systems below their maximum carrying capacity. Aquaponics is a rapidly expanding technology. Every system is unique so it’s really useful to get to know how your own system performs before committing to a full-scale operation.
- Install in a low-cost polytunnel. If you, like most gardeners, prefer a fully productive system rather than pure display then put your aquaponic system in a polytunnel or greenhouse. Weather proof gardening without bending is a wonderful thing for many of us.
- Install a small lighting system. Demonstrate the connection of light and plants. and extend the growing season.
- Pick the fish that’s right for you. Obvious really! To help you decide see our advice on best fish for aquaponics fish.
Finally, if you would like to find out more about this scale of operation I can recommend the following book by Sylvia Bernstein – Aquaponic Gardening by Sylvia Bernstein
Have I missed anything out? Share your thoughts and help make this a better resource for everyone.