Different Types of Aquaponic systems

While all aquaponics systems have certain elements in common, there is a lot of variety in the ways in which these elements are combined. There are a number of different types of aquaponic system, each of which may be the best solution to implement in a given situation. To help you begin the process of deciding which system might be the best for you, here is a brief guide to the most common aquaponics systems:

Media Bed Constant Flow:

The most simple form of aquaponics involves the use of beds filled with a growing medium. The best media for these beds and the depth required for optimal plant growth are hotly debated and will depend on your requirements, location and the other elements of your system. There are two main ways to introduce the water from your aquaculture component into these media beds – the first is to maintain a constant flow, the second, which we will discuss in a moment, is ebb and flow. Constant flow, also sometimes referred to as constant flood, has the advantage of requiring a smaller sump as, unlike the alternative, your system will not have to deal with fluctuating water levels. You may not even require a sump at all, though some say that it is a good idea to include on as this means you will not have to top up the water in the system as often. Another advantage of constant flow systems is that these are easier to expand and you can add a new bed to expand the system more easily than with an ebb and flow system.

Media Bed Ebb and Flow:

Ebb and flow (also known as flood and drain) systems are ones in which the water is pumped intermittently at certain intervals into the media beds. This system is said to be better at removing solids from the media beds and some say that intermittent flooding will introduce more oxygen to plant roots and to the water in the system. However, studies done into the differences between constant flow and ebb and flow seem to suggest that both systems have the same outcomes and which one you opt for will have little (if any) impact on the speed of plant growth or the efficacy of the overall system.

 

 

Deep Water Culture:

In aquaponic deep water culture (DWC), plants are not grown within a medium such as clay or rock as in the media bed systems described above but are instead floating on top of the water with their roots dangling into it. Rafts holding plants float on top of tanks or, more commonly in a commercial system, in channels down which the water from aquaculture tanks will flow. This system has the benefit that, due to the tanks or channels beneath the plants, more water is held within the system. This means that the nutrient solution will be more stable and the whole system will require less monitoring than systems where far less water is used in the loop. Once set up, these systems are pretty low maintenance.

Nutrient Film Technique:

One system of hydroponics which does use very low levels of water is the nutrient film technique in which crops are grown in lightweight drain piping/ guttering through which a thin trickle of water from aquaculture tanks runs. This form of aquaponics is only suitable for a certain range of delicate, leafy plants as other plants will be too heavy or have root systems that become too strong and invasive. For growing salads, however, this can be a truly efficient and sustainable solution.

Wicking Beds:

The final growing method used within aquaponics systems is the wicking bed. Wicking beds are traditional raised beds filled with dirt that sit on top of a reservoir of water – this reservoir of water can be part of an aquaponic system. This type of bed can allow other vegetables to be grown as part of an aquaponics setup that could not be grown in other media or using the other methods above, such as root crops.

Educating yourself as to the pros and cons of each of the above systems is essential if you are to develop the aquaponics system that is right for you.

What is Aquaponics?

Aquaponics

Aquaponics is a portmanteau term which combines the words ‘hydroponics’ – growing plants with water – and ‘aquaculture’ – raising fish and other aquatic species. All aquaponics systems combine the growing of leafy crops with the rearing of water-dwelling animals. As a food production system, aquaponics systems have various advantages over other methods and can be part of a sustainable solution to feeding the planet’s ever-growing population. There are a number of different systems that all come under the umbrella of aquaponics and aquaponics systems can vary greatly in scope and scale.

 

All aquaponics systems, however, will share certain characteristics in common, including the basic nutrient cycle which allowing the two food production systems to work holistically together. Speaking simply, aquaponics systems are low-waste systems. The excretions of the fish or other aquatic creatures being kept in a traditional aquaculture system will gradually build up over time, necessitating their removal to prevent the water environment of tanks from becoming toxic to their inhabitants. In aquaponics, the excrement laden water is fed to a hydroponic system. Bacteria will break down the waste in the water into nitrates, which can provide nutrition to plants whose roots dangle into the water from the aquaculture tanks. This water, cleansed by the plants roots, can then be fed back into the tanks that it came from.

Aquaponics systems are used both in small, domestic settings and huge, commercial-scale endeavours around the world. While the systems can differ greatly, they do all share the three main live components – fish or other water creatures, plant life and the bacteria that allow for the conversion of ammonia in waste to nutritional nitrates that can be made use of by the plants. Some systems also have additional living components, such as worms, or larvae bred to feed the fish or other sea creatures.

Though different aquaponics systems will operate somewhat differently, the following components are usually required: firstly, a tank in which to rear the fish or other water creatures, a settling basin which will catch uneaten food and larger particulates that cannot be filtered out by plants, a biofilter where nitrification bacteria can grow, the hydroponics section where plant growth and plant water-filtering occurs and a sump, to and from which water is pumped en route back to the rearing tanks. In rudimentary aquaponics systems, some of the above components may be combined and the system can also be more complex in more advanced systems.

The living components in an aquaponics system will also require water (or course), light and oxygen and any such systems must take all environmental needs into account – including the temperature and control of pests and disease. A well designed aquaponics system can minimise the use of polluting energy sources, water and land and can create a system run on renewables which is far more sustainable than many other forms of food production.

Growing for Profit

Aquaponics systems are well suited to the development of food production businesses. In many ways aquaponics systems are not only ethical systems which can feed people in a sustainable way but can also help food producers to turn a profit. The key thing when developing a commercial aquaponics system is to understand the benefits of aquaponics and how all elements of a system can be optimised to allow it to function as a viable business in a capitalist world.

The first thing to think about is the system as a whole. The fewer non-renewable inputs are required to keep the system going, the more sustainable it will be and therefore the more viable it will be as a business venture in the long term. For this reason it is important to choose a system that is as renewables based as possible – all electrical power, for example, should come from alternative energy sources such as solar or wind power, ideally, that power will be generated on site to reduce bills and maximise long-term profits.

An aquaponics system can help you to make the most of all resources at your disposal. Land is a major investment for a profit-making business and an aquaponics system can be a good way to maximise the yield on that land. Likewise, aquaponics systems can be far more water-efficient than other food production methods. In some cases, it may be possible to make the most of natural rainfall or other local water sources to further reduce expenses. In a world where climate change is already beginning to bite, water conservation must be a priority for all businesses moving forward.

Another thing to consider in terms of minimising input and maximising profit is whether the system can be used to provide for the food needs of the fish or other aquatic creatures or whether feed will have to be bought in. A sustainable aquaponics system tries to be as self-sufficient as possible. Worms bred through composting of plant waste/ kitchen waste are one sustainable solution to reduce the cost of keeping aquaculture animals and maximise the profits of an aquaponics business. Other possibilities include growing duckweed or micro-algae such as spirulina to feed fish or to create whole ecosystems that can be more or less self-sustaining with far less input from the business owner.

When it comes to maximising profit in an aquaponics system, it is also important to consider which live components to incorporate in your system and what your yield will actually be. Before choosing which aquatic species and which plants to incorporate in your commercial aquaponics system, it is a good idea to do some market research to discover which will bring the highest profit where you live. Some yields will always be higher value than others but some will depend on the location of a business and the needs and preferences of the local community.

Research is key to the creation of a profit-making aquaponics system though with the right information, almost anyone can use aquaponics to make a profit.

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Best Fish Choice for Your System

One of the key decisions when developing an aquaponics system is, of course, which fish or other aquatic creatures to use within it. Here are some of the most common choices used in aquaponics:

Edible Fish For Aquaponics Systems:

 

  • Tilapia: Are quick growing and good to eat, can withstand very poor water conditions and eat plant material and so are cheap to feed. They are one of the most common and best options for many aquaponics systems but require warm water and so will require more energy use in colder climates.
  • Trout: Good to eat, very fast growth rate, excellent food conversion ratios, trout can be a good option for aquaponic systems but will require non-plant food and will eat smaller fish.
  • Carp: Edible, though perhaps not as good to eat as trout and some other freshwater fish, carp reproduce easily and can adapt well to a range of different environments.
  • Catfish: Pretty good to eat, must be skinned. Fast growing and good food conversion ratios.
  • Largemouth Bass: Strong tasting compared to other fish, though edible. Better taste in lower water temperatures.

 

Tilapia are the best choice for warmer climates while trout are usually regarded as the best choice for those living in cooler temperate zones.

 

Non-Edible Fish To Feed Plants:

 

  • Goldfish
  • Koi

These fish (both technically carp) are not edible but are used in some aquaponics systems to feed plants.

 

Other Aquatic Creatures That Can Be Used in Aquaponic Systems:

 

  • Freshwater Mussels
  • Crayfish
  • Freshwater Prawns

All of these can be useful elements in an aquaponics system and may sometimes be used in conjunction with fish.