is a combination of aquaculture (the growing of fish) and hydroponics (the growing of plants in water without soil). This integrated system works so well because the two form a symbiotic relationship and nutrients and resources are recycled between the two. The fish provide waste, which the bacteria turn into plant nutrients, providing the plants with food and the fish with clean water. Indeed, bacteria is the linchpin which keeps the whole system running.
With regards to the set-up,
It is actually very simple. You have the fish tanks, in which you grow fish, and on top of the tanks sits the grow bed. The grow bed is the surface in which the plants are rooted and is the location of most of the bacteria in the system. The grow bed can be made of different materials, but a common one is gravel. Gravel is ideal because it filters the water and provides support to the roots. In addition, it has a large surface area and can house a large number of bacteria.
In an Aquaponics system,
water is pumped from the fish tank to the grow bed, where the bacteria reside. The bacteria break down the fish waste and convert it to nitrates, an excellent fertilizer. The plants take up the nitrates and some of the water, and in the process filter the water. The water is then returned cleaned to the fish tank via gravity.
- The fish, normally something edible like tilapia, poop in their water.
- This poop water is pumped into the hydroponic plant beds, where the detritus provides nutrients for the crop. The nitrates in the water are great for plantsbut will become toxic for the fish, so this is a double win.
- The water usually runs through a filter, though smaller systems may not have filtration.
- The cleaned water is circulated back into the fish tank.
- Repeat until harvest.
“Your ability to turn fish waste (ammonia) into nitrites, then nitrates (plant food) depends largely on the size of your grow beds. Your grow beds harbour your bacteria colony that do all the work, and the more surface area you have, the more fish you can carry.”
Fish/plant ratio in aquaponics
The basic calculation will be based on
Fish tank volume / Grow bed/area or volume.
In a home aquaponics system this ratio is normally 1:1 but in a commercial setup you can increase this to 1:3 or 1:4 depending on the fish density and water flow rate. Commercial systems can stock fish as high as 1 fish per 8-10 liters of water, provided you have ample aeration and Fast water cycling
Minor factors include
Type of aquaponic setup [Growbed/ DWC or vertical]
Choice of fish [some fish generate more waste than others in my experience]
Choice of crops,
The maturity of the aquaponics system,
Aquaponics has many advantages,
It is the most sustainable and cost-effective method of food production. It saves you money, and provides you with fresh organic food from your own backyard. It doesn’t take much space and can be located anywhere: in the backyard, in a spare room, in the garage, etc… It is very flexible, as you can grow a large variety of vegetables and fish. It is environmentally friendly, as no water is wasted and it produces no harmful by-products. Aquaponics is also much easier to run than a conventional soil farm or fish farm – there is no weeding, no watering and no addition of fertilizers and harmful pesticides.
Advantages of aquaponics systems;
- Water conservation is high as there is minimal waste
- There are also minimal waste disposal due to recycling
- No disease-causing organism as opposed to conventional farming
- Both plant and fish enjoy and organic growth in such ecosystem
- High production density (lots of stuff in a small space)
- Self fertilizing system (closed loop) where the fish provide nutrients for the plants and the plants clean the water for the fish.
- A secondary production stream (fish harvesting)
- Superior temperature regulation due to the large thermal mass of the water.
- Floating raft systems provide a conveyor type production line for crops.
- A very wide range of compatible plants (from lettuce to tomatoes to herbs to even banana trees)
Disadvantages of aquaponics;
- High initial cost when setting up the system
- Any mechanical failure in the system can lead to serious damages in the entire system
- It requires energy supply so as to run the electric circuits and aerators
- The cycling process must be completed before the system starts to function which takes time as opposed to hydroponics
- If you have a power failure, the fish may die.
- Media beds can become clogged in time, requiring extensive cleaning (adding composting worms seems to help a lot).
- It’s a more complicated system, and so there is more to go wrong compared to alternatives.
- It’s an isolated and simple ecological system which means when a pest or disease gets in, it’s difficult to eradicate.