There are many ways to do aquaponics.
Most people start out with a backyard system that uses some form of media in which to grow the plants. This media can be certain kinds of washed river rock, lava rock or scoria, expanded shale, manufactured clay pebbles, or other materials.
The aquaponics system is constructed so that the water from the fish tank can circulate through the growing media where the plants are planted, and then return to the fish tank. Often there is a ‘sump tank’ that is the lowest part of the system that collects the water from multiple grow beds, which is then pumped back in to the fish tank. Other people have converted Koi ponds by putting a pump in the pond to pump the water up in to growing beds, from where it then returns to the pond by gravity.
Most commercial aquaponics systems use a combination of media beds and floating raft (‘deep water culture’) systems. The media beds provide additional area for the beneficial bacteria that convert the fish wastes to plant food to live, and filters out any big globs of fish poo that might stick to the roots of the plants in the raft system. The rafts are the most labor saving way to grow and can provide a continuous “conveyor belt” harvest of plants every day.
There are also vertical growing towers and wall mounted growing systems.
The newest way to grow aquaponically is with ‘wicking bed’ systems. In these systems the aquaponics water is circulated under a supported growing medium which ‘wicks’ the water up in to itself to provide just as much water as the plants need. With these systems is it is possible to grow root crops, as well as most other crops. “Air pruning’ pots with there bottom placed into the aquaponics media so they can wick up the water they need look to be very promising way to grow.
Another way to help plants grow is “One-Way” aquaponics – although it really isn’t aquaponics since the water is not recirculated. In this method you simply use the water from the fish tank or pond to water your plants that are growing in the soil. This works very well with fruit trees (but does not save water since you have to replace the water used) because every time you water the trees you are also fertilizing them.