Introduction to Aquaponics
Aquaponic Systems
Aquaponics systems should be very low
maintenance compared with ground-grown crop production and aquaculture.
Feeding and water quality are the
main inputs that will take up the user’s time after the initial build.
Water quality testing should be done weekly in an established system (once it has fully cycled), and more frequently in a new system is just beginning (being cycled). pH should be monitored every other day as this will be a key early indicator of problems occurring in the system.
There are a wide variety of Aquaponics systems and designs that are used in both commercial and hobbyist settings.
The three most common systems in usage.
A) NFT (Nutrient Film Technique) – used mainly in hydroponics
B) Flood & Drain system – (most common hobbyist system)
C) Raft system – (most common in commercial systems)
Water quality testing should be done weekly in an established system (once it has fully cycled), and more frequently in a new system is just beginning (being cycled). pH should be monitored every other day as this will be a key early indicator of problems occurring in the system.
There are a wide variety of Aquaponics systems and designs that are used in both commercial and hobbyist settings.
The three most common systems in usage.
A) NFT (Nutrient Film Technique) – used mainly in hydroponics
B) Flood & Drain system – (most common hobbyist system)
C) Raft system – (most common in commercial systems)
NFT (Nutrient Film Technique)
NFT (nutrient film technique) system has been widely used in hydroponics for many years. NFT can be used in a hobbyist or commercial setting but is the least commonly used with aquaponics. Using this method the plants are placed in pots and a small amount of water (or a film of water) is trickled through the base of the channel from which the roots access the water.
A principal advantage of this system in hydroponics in comparison with others is that it greatly reduces the volume of nutrient solution that is required. However, this is not a positive in aquaponics as the larger quantity of water the more chemically stable it is. This system may be more easily heated during the winter months to obtain optimal temperatures for growth, or cooled during hot summers to avoid bolting and other undesirable plant responses, as well as stress for the fish. However, this is one of the main issues of this system as over the course of a few meters the water temperature in the NFT pipes can heat dramatically.
Although least used, this system is highly versatile in that it can be layered vertically and wall space can be used. It can also be extended very easily and is the lightest in weight.
A principal advantage of this system in hydroponics in comparison with others is that it greatly reduces the volume of nutrient solution that is required. However, this is not a positive in aquaponics as the larger quantity of water the more chemically stable it is. This system may be more easily heated during the winter months to obtain optimal temperatures for growth, or cooled during hot summers to avoid bolting and other undesirable plant responses, as well as stress for the fish. However, this is one of the main issues of this system as over the course of a few meters the water temperature in the NFT pipes can heat dramatically.
Although least used, this system is highly versatile in that it can be layered vertically and wall space can be used. It can also be extended very easily and is the lightest in weight.
Flood & Drain
Media based (also known as flood and drain) is the most common design used in hobbyist systems. It consists of a grow bed filled with a ‘grow media’ normally consisting of either gravel or clay pebbles. The plants are sown or planted directly into the media. As the name suggests the grow beds are flooded and drained periodically, allowing water to circulate through the system on a regular basis. The grow beds themselves must be 30 cm deep in order for the roots to develop properly. The most popular media are the clay pebbles, as they are designed to absorb water and keep the plant roots moist, they are also have a large surface area for the bacteria to colonize. They are also chemically inert.
The advantages of these systems are that they often don’t need an additional filter or clarifier so the maintenance is reduced and less waste is removed from the system. The solid waste is broken down at the bottom level of the grow bed by the bacteria and worms that slowly get introduced over time. Another advantage to the system is its simplicity to build. It is a great system to introduce yourself to Aquaponics with.
The main disadvantages of the system come with elements such as weight – the weight of all the gravel can cause problems. It is important also to be aware that some gravel can change the water chemistry causing problems with the system. The timer or automatic siphon (the way the water is drained back to the tank) can have its own problems.
The advantages of these systems are that they often don’t need an additional filter or clarifier so the maintenance is reduced and less waste is removed from the system. The solid waste is broken down at the bottom level of the grow bed by the bacteria and worms that slowly get introduced over time. Another advantage to the system is its simplicity to build. It is a great system to introduce yourself to Aquaponics with.
The main disadvantages of the system come with elements such as weight – the weight of all the gravel can cause problems. It is important also to be aware that some gravel can change the water chemistry causing problems with the system. The timer or automatic siphon (the way the water is drained back to the tank) can have its own problems.
Deep Flow Raft
Deep flow/raft is mainly used for commercial or larger systems. The grow beds are essentially long troughs of water, the plants sit on rafts made from styrofoam with holes for pots to allow the plants to sit with their roots immersed in the water. The channels must be roughly 30 cm deep, normally a meter or so wide and can be any length. They are the rarely used in hobbyist systems because they require more work to build and maintain as they have many more components than the simple flood and drain.
The advantages of this system are the large water volume, as the water chemistry is more stable alongside the temperature.
The main disadvantages are more aeration of the water is required in the water troughs in order to stop root rot as the roots will always be submersed in water. Problems with evaporation and algae can be more prevalent in these systems. The crops can also be restricted to mainly salad vegetables as the weight of larger plants such as tomatoes and cucumbers cannot be supported easily on the Styrofoam rafts.
The advantages of this system are the large water volume, as the water chemistry is more stable alongside the temperature.
The main disadvantages are more aeration of the water is required in the water troughs in order to stop root rot as the roots will always be submersed in water. Problems with evaporation and algae can be more prevalent in these systems. The crops can also be restricted to mainly salad vegetables as the weight of larger plants such as tomatoes and cucumbers cannot be supported easily on the Styrofoam rafts.