Aquaponics is simply the combination of aquaculture (raising fish) and hydroponics (growing plants without soil). Hydroponic food production is a very effective way of growing large amounts of food, but it requires expensive nutrients to feed the plants, and periodic flushing of the systems which can lead to waste disposal issues. Recirculating aquaculture produces huge quantities of fresh clean fish but excess nutrients must be removed from the system, typically by replacing some percentage of the total water volume, often on a daily basis. However, when we properly integrate hydroponic and aquaculture systems you can capitalize on the benefits of each and eliminate the drawbacks. In fact, some of those former negatives are actually turned into assets of the system.
There are three types of aquaponic systems, which I will provide some detail on below, and they all work on the basic principles. Fish, such as talapia or catfish, are raised in a large tank. They are fed which, of course, leads to the fish producing waste (amonia and solids) and making the water “dirty”. It just so happens that this dirty water is the perfect organic food source for the plants, so it is pumped from the fish tanks into the plant beds. Once there, microbes (nitrifying bacteria) and in some cases worms go to work converting the the fish waste into forms of nitrogen that plants can uptake and use to grow. This cleans the water which is then returned to the fish tanks. Overall, aquaponics is a very efficient, effective, and sustainable method of producing large quantities of high quality organic food.
Nutrient Film Technique (NFT)
Nutrient Film Technique is a very common method in hydroponics, but probably the least common method used in aquaponics. In NFT aquaponic systems, the nutrient rich water is pumped out of the fish tanks and down small enclosed gutters in only a very thin film. The plants sit in small plastic cups in the top of the gutters allowing their roots to access the water film and absorb the nutrients. The use of NFT is limited as it is only really suitable for certain types of plants, generally leafy green vegetables, because it does not provide much room for large root systems or any form of support for larger, heavier plants. It is, however, perfect for taking advantage of vertical space.
Media filled beds are the simplest form of aquaponics making it the most common method for small to mid-sized home systems. These systems use a raised bed filled with a porous expanded clay or shale rock media. The media provides both the biological filtration (conversion of ammonia to nitrates) and mechanical filtration (removal of solid wastes) in the same system. Similar to soil based gardening, it also provides a solid foundation for larger fruiting plants allowing for the widest range of plant cultivation options.
Deep Water Culture (DWC)
Also called raft based growing, DWC is the most efficient method of quickly growing large quantities of food, however, it is the most technically complicated and you are limited to growing salad greens and other fast growing relatively low-nutrient plants. This makes it ideal for larger commercial-scale production which is where you will see DWC most often utilized. In DWC, the waste water from the fish tanks is pumped through a filtration system and then into large grow channels with foam rafts floating across the surface. Plants are placed in holes in the raft and the roots dangle freely in the nutrient rich water.
Regardless of which one of these forms of aquaponic systems you are utilizing, they all share some pretty significant advantages over traditional gardening/farming.
- Aquaponic gardening is much less physical demanding as it eliminates bending, stooping, weeding, digging, etc.. Gardening chores are greatly reduced if not eliminated entirely.
- Small animal and most pest access to your garden is no longer an issue.
- Aquaponics relies on the continuous recycling of nutrient-rich water, using 1/10th the water of soil-based gardening without any of the toxic run-off of hydroponics or aquaculture.
- No chemicals, pesticides, of herbicides are used. It is a natural ecosystem that produces nutrient rich food.
- It can be done anywhere on almost any scale! Outside, a greenhouse, your garage, or ever your kitchen counter top.
There are many great resources out there for those that would like to learn more about aquaponics. For those of you that like to learn via video, I enjoy and have learned a lot from The School of Aquaponics and Murray Hallam Aquaponics channels on YouTube. If you are the type that prefers to read and have a hard copy on hand, I highly recommend Aquaponic Gardening by Sylvia Bernstein and The Bio-Integrated Farm by Shawn & Stephanie Jadrnicek.