NFT Aquaponics: Nutrient Film Technique + Aquaculture

Aquaponics is a series of growing methods based on several hydroponic techniques. NFT aquaponics is one of the most successful methods.

But, What is NFT aquaponics, exactly?

NFT aquaponics is a modified hydroponic technique that revolves around a thin stream of water that is slowly but surely forced up and out of fish tanks and along grow pipes. This movement of water allows plants to suck up all the water, air, and nutrients they need.

In this article, we discuss NFT aquaponics in much greater detail. Read on to learn how it works, the benefits, the disadvantages, how it stacks up to other popular growing systems, and much more.

How Does a Nutrient Film Technique Aquaponic System Work?

NFT Aquaponics systems utilize several crucial components; a fish tank, growing pipes, water pump, and a sump tank or biofilters. 

Water flows from the fish tank into the growing tray via a pump and is distributed through the system’s pipes. 

Some of the water is absorbed by the plants’ root systems and the rest is then recirculated through the system.

NFT Aquaponic Basics

The basic principles of NFT aquaponics are quite simple compared to other sorts of “advanced” growing systems. NFT aquaponics centers around plants that are grown in long and narrow channels, typically consisting of food-grade PVC pipes.

NFT Aquaponics System With PVC Piping

The main difference between NFT aquaponics and NFT hydroponics is that the reservoir houses live fish. Further, with hydroponics, nutrients are added by hand. In aquaponics, the nutrients are created by the fish.

Once pumped from the fish tank, water passes through the system and creates a constant flowing thin film of water and nutrients. This thin film is where the plants absorb everything they need to grow and thrive, including oxygen.

After running its course through the grow pipes, the water is directed back through the system where it passes through a sump tank or filter and then into the fish tank.

NFT Aquaponic System Components & Setup 

The basic components of NFT aquaponics systems include:

  • Fish tank. The reservoir that holds the majority of the system’s water, nutrients, and of course, fish.
  • Filter or sump tank. These are optional parts in some NFT systems, but they do help out tremendously at reducing bacteria and preventing disease.
  • Water pump. A vital part of any NFT aquaponics system, this unit moves the water up and out of the fish tank and into the rest of the system including the grow sites.
  • PVC pipes. These are the components that house the grow sites, net pots, growing medium, and actual plants.
  • Rubber hoses, or PVC tubing, and fittings. Hoses, tubes, and fittings help piece everything together, as well as prevent leaks and evaporation.
  • Rockwool or similar growing medium. The best NFT systems include growing mediums housed in net pots, this allows the plants to stay firmly anchored in position and develop healthy roots.

Set up a basic NFT aquaponics system

  1. Measure the area you want to set up your system in and either purchase or build a rack for housing the grow pipes.
  2. Cut or purchase the correct length of PVC pipe for the grow pipes and then drill or cut holes every several inches for the actual grow sites. Don’t forget to add a hole on the bottom of the lowest grow pipe in the system for the drain pipe. Once the rest of the system is pieced together, connect the drainpipe to this hole and place the other end of the pipe where it can drain into the fish tank.
  3. Mount the grow pipes to the frame, use a level to make sure it’s stable and allows for good water flow.
  4. Set up your fish tank by adding water, testing the pH level, and adding the proper fish.
  5. Measure the correct lengths of rubber hose or small PVC tubes, and fittings, and connect them to the system. One end connects to the water pump in the fish tank and the other end(s) to the highest point(s) of the grow pipe(s).
  6. Turn on the pump and test your system. Make adjustments as needed and have patience.

Benefits of NFT Aquaponics (Pros)

NFT aquaponics has several advantages over other growing systems:

  • The system is organic, no chemicals are needed
  • The constant flow of water reduces the risk of harmful bacteria or disease occurring
  • Plants’ roots are free to absorb as much water, oxygen, and nutrients as they need
  • Roots are exposed to plenty of fresh oxygen, which boosts their growth and helps prevent root rot.

Drawbacks to an NFT Aquaponic System (Cons)

There are also a few common disadvantages with NFT aquaponics systems:

  • Fewer types of crops are available for growing
  • System failure is not uncommon due to pump failure or other factors
  • Water temperature may be trickier to control than in other systems
  • Roots may grow large enough to clog the grow pipes/grow sites

NFT Aquaponics Maintenance: How Much Work Is Involved?

Maintaining an NFT aquaponics system requires a bit of work, sure. But, what sort of growing system doesn’t?

One of the most important maintenance tasks with this form of aquaponics is keeping the fish tanks balanced. Baby fish need to move to another tank until they are full-grown, for example. 

Likewise, adult fish that die or become sick need removing as well.

In addition, the fish need to be fed very carefully. Avoid overfeeding them and always skim out any uneaten food that the fish leave in the water.

Remember, fish are the heartbeat of your system. They provide all the nutrients and keep the water healthy.

NFT systems also require a full cleaning every couple of weeks, which is one of the most tedious tasks but a crucial one. While cleaning the system, replace water, clean filters, wipe down pumps, and clean the growing pipes as thoroughly as possible.

What Type of Filtration Is Needed for NFT Aquaponic Systems?

Filters are not a necessity in most aquaponic systems due to the fact that the fish work as filters. But, it definitely doesn’t hurt to add one as it will only help make your fish’s job easier.

That said, many of the submersible water pumps utilized in hydroponic and aquaponic growing systems come with built-in filters. If the pump you choose doesn’t come with a filter, consider purchasing and installing one separately.

There is no one sort of pump that is required for NFT aquaponics. Fountain pumps, pond pumps, or hydroponic pumps are preferred.

Depending on the size of your operation, the strength required of your pump varies.

For a small NFT system, a pump that is capable of pumping at least 30 gallons of water a foot or two higher than your system is ideal.

Choosing the right pump for your system isn’t a hard task, it’s simply one that requires a bit of research on your part.

Best Plants for NFT Aquaponics 

The best plants for NFT aquaponics typically fall into one or more of three categories:

  1. Small leafy vegetables
  2. Root vegetables
  3. Plants with quick bloom/harvest times

Among the most popular plants to grow for NFT aquaponics include lettuce, spinach, micro-greens, bok choy, broccoli, cauliflower, radishes, and turnips.

What Plants Will Not Work With an NFT Aquaponic System? 

Unlike other types of hydroponic grow systems that allow for larger plants, NFT aquaponics will not grow plants that have large root systems, like trees and bushes. They also aren’t suitable for plants that grow tall, like corn, sunflowers, or certain types of tomatoes.

Does NFT Aquaponics Use a Growing Medium? 

Just about every type of aquaponics works well with a growing medium in addition to net pots. NFT aquaponics is no exception.

The most commonly utilized growing mediums for NFT aquaponics grow systems include Rockwool, grow sponges, clay pellets, and loose gravel.

That said, depending on how large the grow pipes are, and what sort of plants you’re growing, it is possible to operate an NFT system and grow plants directly in net pots without a growing medium.

What Size Grow Pipes Are Best for NFT Aquaponics? 

The best size grow pipes for NFT aquaponics are generally 4-inch in diameter. Pipes this size allow plenty of space for net pots, growing medium, and root development. It also allows for a free-flowing film of water and nutrients.

However, if you are using a smaller than average NFT system or have a focus on small leafy vegetables only, a two-inch or three-inch grow pipe setup could work just as well.

Likewise, if your goal is to cultivate crops of larger plants, such as peppers, tomatoes, or melons, you may opt for even larger pipes. In this case, five-inch or six-inch pipes are more than suitable.

Spacings between each grow site in the pipes should be set at between four and eight inches depending on the size of the plants you wish to grow.

How Many Fish Do You Need for NFT Aquaponics? 

There is no exact amount of fish that works best for NFT aquaponics, unfortunately. You need to perform a bit of research and experiment as well.

There are, however, a couple of general rules of thumb that may help you find the right amount of fish for your specific NFT system:

  • For every grow site in your system, add an equal amount of fish to the reservoir
  • For every five gallons of water that your system holds (give or take a gallon or two) add a pound worth of fish (ie: two half-pound fish, one pound fish, or four quarter-pound fish)

What Other Hydroponic Methods Can Be Used in Aquaponics?

Aquaponics can be practiced with any of the six main hydroponic growing methods (besides the NFT method) by taking away standard reservoirs and adding appropriate fish tanks.

The other hydroponic methods that can be used in aquaponics include, but are not limited to:

  1. Deep water culture. Plant roots are semi-submerged in water that is fed oxygen and nutrients in DWC systems.
  2. Wicking. Water and nutrients are fed directly to the plant’s roots via a wicking system.
  3. Drip. A constant supply of water and nutrients is slowly dripped over the roots of plants in this type of system.
  4. Ebb and flow. Timers and water pumps systematically flood and drain the roots of plants in what is known as the ebb and flow hydroponic method.
  5. Aeroponics. This popular hydroponic technique involves growing towers where plants’ roots are suspended in the air and misted or sprayed with water and nutrients.

In addition to these main hydroponic methods that work for aquaponic systems, there are several experimental and hybrid methods as well. These types of aquaponic grow systems are not as stable, are often DIY, and should be heavily researched before trying them at home.

What’s the Difference Between NFT and DWC Aquaponics?

As discussed above, NFT aquaponics involves fish tanks, filters or sump pumps, water pumps, hoses, tubing, fittings, and pipes. The grow sites are located in the pipes, and the water is pushed into them at a slow but steady rate. 

The root systems of plants are never fully submerged in NFT systems. Rather, they are constantly exposed to a small amount of water and nutrients (the film).

In DWC aquaponics, or deep water culture hydroponic systems in general, the setup is much more basic. 

The biggest difference between DWC and NFT is that the roots are submerged in the water with DWC systems as opposed to the constant thin layer of flowing water utilized in NFT systems.

The fish tank and grow tray may even be one and the same if the DWC system is a small one. If so, the net pots are usually inserted through a lid on top of the fish tank.

In larger setups, a fish tank may pump water into several deepwater reservoirs with lids that hold plants in place with their roots dangling and submerged in the water and nutrients.

Final Thoughts About NFT and Aquaponics

The nutrient film technique aquaponic growing method is basic, but still more advanced than simple aquaponic like DWC or wicking systems. They aren’t the hardest systems to set up and operate, but they also aren’t the easiest.

If you plan to try your hand at NFT aquaponics, steady patience, loads of practice, and plenty of research are a must. But, if you put your mind to it, and your pocketbook, you should have no problem with building and running an NFT system.