Look at existing types of aquaponics systems
There are many kinds of aquaponics systems. They mostly differ by the arrangement of their elements, type of tanks, used technologies and size. Here you’ll find their overview.
The most common kinds of fish in aquaponics
The most bred kind of fish in aquaponics is the Nile Tilapia (Oreochromis Niloticus). The Tilapia requires warmer water, but offers good meat, endurance and fast growth. In the USA it belongs into the most favorite freshwater fish and therefore it’s breeding and selling there is relatively easy. Others, mostly in Australia bred fish are various percinae fish (breeding of Nile Tilapia is banned in Australia). Rainbow Trout (Oncorhynchus mykiss) is the other possible choice for aquaponics breeding. This kind is also perspective for Europe conditions because it is popular consuming fish there, but it requires high quality water. Another fish that can be bred in aquaponic systems is grass carp or pangasius, eventually even carp. Koi and decorative Crucians are the most common bred fish that aren’t used to consumption. They are mostly used in demonstrative systems or in decorative aquaponic ponds.
The most commonly grown plants in aquaponics
The oldest and still grown plant is Watercress, Nasturtium officinale. It is an undemanding water plan with little spicy taste, which is used in salads and is popular in France. Nowadays the most grown plants are mostly various kinds of salads and leaf vegetable, which grows very well on floating rafts. Other vegetables are tomatoes, paprika or chili peppers. Some growers are experimenting with root vegetable. Many kinds of herbs are also very favored, for example basil. From fruits, which is also very popular in aquaponics, strawberries are the most popular. These are usually grown in NFT systems or vertical towers (read below).
An aquaponics systems can be divided by their size to:
Nowadays you can buy commercially available aquaponic „mini systems“ from producers from Australia and USA. These assemblies can be an interesting addition to the kitchen, however their functionality is problematic. Small volume of water is prone to swings in a quality and these small aquaponics have to be cleaned as often as common aquariums. Plants in them will suffer from lack of some nutrients and light stress from uneven lighting.
Hobby and garden systems
These little to medium sizes of the systems are usually placed in private properties of individuals – handy man, who run aquaponics as a hobby. The most used growing substrate is gravel, ceramsite, lava gravel or eventually even floating rafts. In hobby aquaponics earthworms are often added into substrate to help with decomposing organic remains and speed up mineralization. In larger hobby system we can encounter with NFT (read below) and separation of solid waste.
Big commercial systems
Most of existing aquaponic systems designated for selling fish and vegetables belong here. Usually it consists of one or several systems in one greenhouse with growing area of tens to hundreds quarter meters. Growing plants on rafts is by far the most popular method. On the northeast of USA the type with long multilevel tanks from wood and EPDM foil by the design of Will Allen form Milwaukee is very frequent.
Big commercial systems
Into the big commercial systems comes systems with area over thousand square meters.
Another way to divide aquaponics systems is by used technology and way of breeding fish:
Growing in periodically flooded tanks filled with substrate.
It is the most common type of growing used in a small aquaponic systems. It is also called Flood & Drain. The tank is equipped with „siphon“, which after filling automatically drives water away from growing tank further into the system. This way the periodically flooded substrate (ceramsite, gravel) gives the roots of plants ideal environment rich with both nutrients and oxygen. Tanks filled with substrate are also put before growing tanks with rafts as a filter against solid particles and bio filter, where the nitrification happens.
Rafts are mostly represented by polystyrene plates, with holes for baskets or mineral wool with plant seedlings. Plans thus flow on the surface of growing tank that has shape of a shallow pool. Roots of plants then are in water column. Steady water flow or placement of air stones is required for sufficient oxygen and nutrient distribution. Advantage of this system is very easy manipulation with singular polystyrene plates, thus so with plants that are comfortably harvested.
NFT means Nutrient Film Technique. This way of growing is often used in hydroponics and it is a system of pipes with holes for individual plants. Very shallow water flows through the system. Roots of plants get nutrients from film of water and oxygen from the air.
This modified variant of NFT allows growing big amount of flowers in a small place. Water flows through the tower thanks to gravity and distributes nutrients to plants planted in special foamed matter. This kind of growing is sold as ZipGrow towers by Dr. Nate Storey at the Bright Agrotech. This method requires very good filtration of solid sludge that could clog the water distribution and even the vertical tower itself.
This method is ultimate method of hydroponic growing that can be used also in the aquaponics. Roots of plants are sprayed with drops of nutrient solution from special nozzles. This method maximizes roots oxygen supply, which thanks to that absorb nutrients better and thanks to that vegetables grow a lot faster. On the other hand it is very technically challenging and it requires very good filtration system that gets rid of the entire solid waste.
Aquariums are very aesthetic and design solutions for aquaponics in interiors. Because of size limitations they are only used in the small systems. Their advantage is the ability to watch bred fish, which are then often only decorative. Their biggest problem is ensuring good water flow, filtration of sludge and reducing algae growth so that it is always pretty to look at.
It is the most popular type of tanks used for breeding fish and growing plants. IBC are plastic containers for liquids or beverages with outer reinforcing metal cage. These containers are used for transporting various liquids and are very popular by gardeners, who are using them to collect rain water.
Their shape and capacity (1000 liters) makes them ideal for small or modular aquaponic systems and small private breeders often use them to breed fish. Another advantage is presence of the dump valve at the bottom of the tank.
Wood tanks in the multilevel system of Will Allen
This, now almost historical, probably originates from Will Allen from Milwaukee. Tanks are assembled from (larch) planks to fit area of a greenhouse and are covered from the inside with EPDM rubber. Tank for fish is in the bottom part and growing tanks are placed in several levels above them. Water is pumped to the topmost level and then it flows down through each „level“ back to the fish. Advantage of this is significant space savings and large growing area. Disadvantage of this system is mostly bad sludge management, which is filtrated only by gravel substrate. The gravel has to be „washed“ from time to time. Rectangular shape of the fish tank also limits ideal flow of water, which is worse than in a circular tank.
Circular tanks, hatcheries or pools
This is the best type of tank that is little less space saving, however it offers large volumes of water for fish breeding (thousands of liters) and very good water flowing that improves whole aquaponics cycle. Water is usually let in to the tank in one way and this creates a little whirl. This is good for healthy movement of the fish and most importantly concentrates solid part of fish waste in the center of tank. From there the sludge can be moved very fast to the setting or filtration tank. Because of that water in these systems is often very clean. Fish excrements aren’t grinded by airing and don’t set in the corners of tank, but are moved whole further into the system, where they can be processed. The volume of subtle particles, that slowly clog the system, is minimal.
Interesting way to use decorative garden ponds or tanks is linking them with hydroponic bed. However this system is only suited for hot areas, where it is able to grow under the sky for big part of a year (south of the USA, Australia). Hydroponic bed often replaces expensive filtration device. These aquaponic systems are very robust, because they are managed by the nature.