Most aquaponics systems are freshwater systems, where you raise freshwater fish. You need to decide if continuous flow or flood and drain aquaponics (aka ebb and flow) is right for you. Of course there are saltwater systems also, which have come about as people have experimented with raising saltwater fish. The main advantage of freshwater systems is that nearly any kind of crops can be grown with freshwater, including herbs, strawberries, tomatoes, lettuce, and melons.
Different aquaponics systems have one thing in common – they all utilize the fish solid waste and ammonia to fertilize the crops that are being grown. The plants are the other big part of the efficiency of aquaponics systems, and as the water fertilizes the plants, it is also cleaned and renewed with oxygen before being recirculated to the fish.
Home systems are highly efficient and tend to be especially effective for growing all kinds of different organic fruits and vegetables. This is because the plants receive a continual supply of vitamins and nitrates, as the nutrient-dense waste water from the fish is circulated to them around the clock. Unlike aquaculture systems, the water is purified by the plants, and the need to add and replace water each day is eliminated.
The 2 Main Types of Systems
In either of the following two types of systems, you have a new fish aquaponics holding tank where the fish live, and grow beds where the crops are grown. The water from the fish tank is pumped into the grow beds using a sump pump or fountain pump, and the roots of the plants being grown are submerged in the water from the fish tank.
Flood and Drain System
Flood and drain systems tend to conserve electricity, and can have similar results to the continuous flow systems that we will discuss in a moment. In a flood and drain system, a float switch is used to stop the water from pumping when the grow beds for the plants are filled to a specific level.
In this system, the switch often has a floating ball, which is a plastic ball full of air that rests on the surface of the water. This is like how a toilet works. Once the floating ball reaches a certain level, the switch is activated, turning off the water pump.
In a flood and drain aquaponics system, the grow beds can be situated above the fish holding tank. This is the most efficient setup for this type of system, and uses gravity to drain the water from the grow beds back directly into the fish holding tank. Sometimes this type of system uses an additional water holding tank called a sump, which is where the water from the grow beds is drained before being pumped back to the fish tank.
Continuous Flow System
As you can probably imagine, water is continually cycled from the fish to the plant growing beds – where it is filtered and cleaned – and then pumped back to where the fish are at. Usually the crops are situated on rafts, called raft aquaponics, and the vegetation has its roots hanging down into the nutrient dense water. The water is continually circulated through the submerged roots, which can result in rapid growth of the plants.
Continuous flow systems are usually less expensive to build than a flood and drain system, however, more care and monitoring are needed to ensure that all of the plants and grow beds are getting an even amount of water and nutrients. This will prevent “dead spots” in the grow beds, and sometimes the grow beds need to be moved or rearranged for maximum benefit.
With either of these aquaponics systems, choosing the right types of plants and fish is essential. Additionally, the amount of fish and plants that you have in the system will have to be carefully balanced to ensure that the water is being cleaned enough to keep the fish environment clean.