NFT System for Growing Marijuana (Nutrient Film Technique)

The Nutrient Film Technique (NFT) represents one of the most significant advances in the field of hydroponic growing systems, an agricultural practice that dispenses with soil to grow plants, nourishing them exclusively with solutions rich in minerals. This system is characterized by its ability to feed plants with a thin layer or "film" of water enriched with essential nutrients, which constantly flows over the exposed roots within inclined channels, thus ensuring optimal oxygenation and access to nutrients. If you are not familiar with this type of cultivation, we recommend reading this article on what is hydroponics so that you can understand well everything that we will discuss later.

Since its inception, the NFT system has gained considerable popularity among commercial farmers and home gardening enthusiasts due to its efficiency in water and nutrient use, as well as its scalability and ease of automation. Its innovative design not only allows precise control over the plants' root environment, but also facilitates the production of high-quality crops in small spaces and with less manual work compared to traditional soil growing methods. The relevance of the NFT system in modern hydroponics is undeniable, and its application continues to expand, promoting more sustainable and resource-efficient growing practices.

What is the NFT System?

The NFT System, acronym for Film Nutrient Technique, is a hydroponic method that is based on the continuous flow of an aqueous solution rich in nutrients over the bare roots of the plants, which are housed in gutters or tubes. The solution flows in a very thin layer, allowing the roots to have constant access to both nutrients and oxygen from the air. This system eliminates the need for a solid growing medium, as the plants are supported in holes made in the top of the gutters, allowing the roots to hang freely within the stream of nutrient solution.

The history of the NFT system dates back to experiments conducted in the 1960s by Dr. Allen Cooper in England, who was looking for an efficient technique for hydroponic growing that would improve root aeration and nutrient use efficiency. Since then, the system has evolved significantly, going from a scientific curiosity to one of the cornerstones of commercial hydroponics. Over the years, the NFT has been perfected to maximize production in greenhouses and urban vertical farming operations, where space is limited and control over growth variables is crucial.

The simplicity and effectiveness of the NFT system have made it a favorite for both commercial growers and hydroponic hobbyists. Its modular design and ability to scale make it ideal for a wide range of applications, from small home gardens to large agricultural facilities. With the growing interest in sustainability and food security, the NFT system remains relevant and continues to adapt to new technologies and sustainable farming practices.

Components of the NFT System

The NFT system is made up of several essential elements that work together to create a controlled and efficient environment for growing plants. The key components and the function of each are described below:

• Gutters or Cultivation Channels: They are the containers where the plants grow and through which the nutrient solution flows. They are generally made of PVC or plastic and have a slight slope to allow water movement. Gutters should be opaque to keep out light and prevent algae growth.
• Irrigation Tank: It is a container that stores the nutrient solution. It should be large enough to supply an adequate amount of solution to the plants and maintain nutrient stability. It must also be opaque and resistant to corrosion.
• Water Pump: This component is essential to recirculate the nutrient solution from the tank to the gutters. The pump must be of adequate capacity to ensure a constant and uniform flow of the solution.
• Pipes: They connect the pump to the gutters and distribute the nutrient solution. They must be made of a resistant material that does not react with the nutrient solution and that can withstand the pressure of water.
• Supports or Support Structure: These are the frames that hold the gutters in place. They must be strong and stable to support the weight of gutters filled with plants and nutrient solution.
• Return System: It is the set of channels or pipes that return excess nutrient solution to the tank. This allows the solution to be reused, saving water and nutrients.
• Filters: They are used to keep the nutrient solution clean, removing particles and preventing blockages in the system.
• pH meter and EC meter: They are critical tools for monitoring and adjusting the quality of the nutrient solution, ensuring that plants receive the correct balance of nutrients and an adequate pH.

When selecting materials for each component, it is important to consider durability, corrosion resistance, and compatibility with the nutrient solution. The materials must also be safe for growing plants and must not release toxic substances into the solution. Energy efficiency and ease of maintenance are other key factors to consider when choosing components for an NFT system.

Operation of the NFT System

The NFT (Nutrient Film Technique) system operates under a relatively simple but ingenious principle. The nutrient solution is pumped from a storage tank to the gutters or canals where the plants are located. The solution flows over the roots of the plants in a thin layer or "movie", hence the name "Film" in the technique. This film of nutrient solution provides the roots with constant access to essential nutrients as well as oxygen, as the layer is thin enough for the roots to be in contact with both the solution and the air. After passing through the gutters, the solution not absorbed by the plants is drained back to the nutrient tank to be recirculated.

Advantages and Disadvantages of the NFT System

Advantages:

• Better Oxygenation of the Roots: Direct exposure of roots to air ensures high oxygenation, which is crucial for healthy plant growth. Roots need oxygen to perform respiration, which is vital for their metabolism and nutrient absorption.
• Efficient Nutrient Absorption: Since the nutrient solution is constantly moving, nutrients are distributed evenly, allowing all roots the same opportunity to absorb what they need. This prevents the buildup of nutrients in one area, which could cause toxicity or deficiencies.
• Disease Prevention: Good aeration and the absence of solid substrate reduce the risk of soil-related diseases, such as pathogenic fungi that thrive in humid and poorly aerated environments.
• Efficient Use of Water and Nutrients: Recirculating the nutrient solution means less water and nutrients are used compared to traditional growing methods. This is not only more sustainable, but also reduces operating costs.
• Uniform and Controlled Growth: The NFT system allows precise control over growing conditions, resulting in more uniform and predictable plant growth.
• Ease of Monitoring and Adjustment: Since the roots are accessible and the nutrient solution is easy to sample, it is easy to monitor and adjust conditions to optimize plant growth.
• Efficient use of water and nutrients: The NFT system recirculates the nutrient solution, reducing waste.
• Lower risk of soil diseases: By not using soil, many common diseases associated with traditional gardening are eliminated.
• Accelerated plant growth: The constant availability of nutrients and oxygen can result in faster growth.
• Space saving: Vertical or tiered design allows you to grow more in less space.
• Automation: The system can be easily automated, reducing the labor required.
• Monitoring and control: Allows precise control over the root environment and plant nutrition.

Disadvantages:

• Energy dependence: Requires electricity for the pump, which can be a problem in case of power outages.
• Technical maintenance: May require more advanced knowledge to troubleshoot and maintain the system.
• Initial investment: The initial cost may be higher compared to other simpler hydroponic systems.
• Vulnerability to system failures: A failure in the pump or power supply can quickly cause the death of plants.
• Limitations on the type of plants: Not suitable for plants that require a large volume of hydroponic substrate or that are particularly large or heavy.

Comparison to other hydroponic systems:

• Tidal systems (Ebb & Flow): NFT is continuous and uses less water, but tidal systems may be better for larger plants.
• Drip systems: NFT is more water efficient, but drip systems may be better suited for a wider range of plants.
• Aeroponic systems: NFT is less technical and easier to maintain, while aeroponics can provide faster growth but requires finer control and more frequent maintenance.
• Wick systems: NFT is more complex and expensive, but offers better control over nutrients and plant growth compared to the simpler and less expensive wick system.
• DWC Hydroponic Growing System: Unlike the NFT, the DWC immerses the roots in water constantly, ideal for robust plants. NFT is best for quick crop cycles and requires less space.

The NFT system is particularly suitable for short-cycle and fast-growing plants, such as lettuce, aromatic herbs and some varieties of strawberries. Its efficiency and ease of use have made it a popular method in urban agriculture and commercial vegetable production.

Assembling an NFT System Step by Step

Building a basic NFT system requires planning and acquiring the necessary components. Below are the steps for setting up an NFT system along with practical tips:

Step 1: Space Planning and Design

• Evaluate available space for the NFT system, considering light, temperature and weather protection if outdoors.
• Measure the area to determine the size and number of gutters that can be installed.
• Design a system schematic, planning the layout and number of levels or rows of gutters.
• Select the plants that will be grown, which will influence the distance between the planting holes and the capacity of the nutrient system.
• Calculate the inclination necessary for the gutters to ensure optimal flow of the nutrient solution.
• Decide the height of the gutters to facilitate maintenance and harvest.
• Plan access for maintenance, ensuring that all parts of the system are easily accessible.
• Determine tank capacity of nutrients based on the number of plants and gutters.
• Consider electrical installation and safety, especially if the system will be mounted indoors. 

Practical tips: 

• Use design software or an application to draw the system plan and make adjustments easily.
• Research specific requirements of the plants to be grown to adapt the design to your needs.
• Consult with experts or experienced growers to obtain feedback on the proposed design.
• Consider energy efficiency and environmental impact when selecting materials and planning the design.
• Forecast future growth and possible expansion of the system to avoid having to make major changes later.

Step 2: Material Acquisition

• Buy gutters or cultivation channels suitable for the NFT system, preferably made of opaque material to prevent algae growth.
• Acquire a nutrient tank sized appropriately for the volume of the system and opaque to reduce light that promotes algae growth.
• Select a water pump with the appropriate capacity for the size of the system and the length of the gutters.
• Get pipes and fittings necessary to connect the pump to the gutters and for the return system.
• Buy or make supports for gutters that can support the weight of the full system.
• Acquire filters to keep the nutrient solution clean and prevent clogging.
• Get pH and EC meters to monitor and adjust the quality of the nutrient solution.
• Purchase additional materials such as clamps, connectors, and tools for mounting the system.
• Consider purchasing a timer if you wish to automate the nutrient solution pumping cycle.
• Select construction materials if elements of the system, such as the support structure, are planned to be manufactured.

Practical tips: 

• Compare prices and quality of materials between different suppliers to find the best offer without compromising quality.
• Check specifications of products, such as pump capacity and material strength, to ensure they meet the needs of the system.
• Read opinions and reviews from other users about the materials and equipment to identify possible problems and advantages.
• Buy some spare parts, such as additional pipes or connectors, to have on hand in case of need or for future system expansion.
• Recycle or reuse materials where possible to reduce costs and environmental impact.
• Make sure all materials are safe for use in cultivation systems and do not release toxic substances into the nutrient solution.
• Plan future maintenance When choosing materials and equipment, opt for those that are easy to clean and maintain.

Step 3: Assembling the Support Structure

• Design or select a design for the support structure that fits the dimensions and number of channels of the NFT system.
• Choose resistant materials for the structure, such as galvanized metal, aluminum or reinforced plastic, that can withstand the humidity and weight of the system.
• Build or assemble the structure following the design, making sure it is stable and level.
• Install the structure in the designated area, verifying that there is enough space around for the maintenance and observation of the plants.
• Ensure that the structure has the proper inclination to allow the flow of the nutrient solution by gravity.
• Reinforce joints and load points to prevent wear and tear and ensure durability.
• Check that the structure is level using a spirit level to ensure uniform flow of the nutrient solution.
• Make adjustments if necessary to ensure all gutters fit properly and are secure in the structure.

Practical tips:

• Use corner protectors and caps on the sharp edges of the structure to avoid injuries during maintenance.
• Consider future expansion when designing the structure, allowing the addition of more channels or levels if it is desired to increase the capacity of the system.
• Include wheels or adjustable legs if a mobile structure is desired or if the height and leveling need to be adjusted easily.
• Protect the structure against corrosion applying paint or sealants if materials are susceptible to rust.
• Make sure the structure allows easy access to the gutters and nutrient tank to facilitate maintenance and monitoring tasks.
• Document the assembly process with photos or notes to facilitate troubleshooting or to replicate the design in future installations.

Step 4: Installing the Gutters

• Place the gutters on the support structure, making sure they fit well and are stable.
• Adjust the tilt of the gutters to allow optimal flow of the nutrient solution, generally a slope of 1 to 3% is recommended.
• Check that the gutters are level in its length to avoid water stagnation and ensure uniform flow.
• Fix the gutters to the structure using clamps or supports to prevent displacement.
• Cut and prepare the holes for plants at the top of the gutters, making sure they are spaced appropriately depending on the type of plant.
• Install gutter ends with plugs or connectors to direct the flow of the nutrient solution and prevent spills.
• Connect gutters to return system if applicable, to recirculate the nutrient solution back to the nutrient tank.

Practical tips:

• Use a ruler or laser level to ensure that the gutters are perfectly aligned and level.
• Test water flow before placing the plants to make sure there are no leaks and that the water is flowing properly.
• Cover the gutters with a lid or opaque material to prevent direct sunlight and reduce algae formation.
• Leave extra space at the end of each channel for future expansion or adjustments to the system.
• Consider access for cleaning and maintenance when installing gutters, ensuring all areas can be easily reached.
• Mark the plant holes before cutting to ensure even distribution and avoid errors.
• Check connections periodically to ensure they remain secure and there are no signs of wear.

Step 5: Irrigation System Configuration

• Install the water pump into the nutrient tank, making sure it is properly submerged and secured in place.
• Connect the pipes from the pump to the gutters, using secure connections to prevent leaks.
• Place drippers or micro sprinklers at the start of each trough, if using this method, to distribute the nutrient solution evenly.
• Ensure a return system for the nutrient solution not to be absorbed by the plants, directing it back to the nutrient tank.
• Install filters in irrigation lines to prevent clogging of emitters and keep the solution clean.
• Regulate pump flow and watering frequency, if using a timer, to provide plants with the proper amount of nutrient solution.
• Check that the irrigation system is working correctly, without dry or over-saturated areas in the gutters.

Practical tips:

• Carry out irrigation tests before planting to ensure the entire system is working as expected and adjust as necessary.
• Use dark colored pipes or cover them to avoid exposure to light and reduce algae growth inside them.
• Keep the nutrient solution moving to prevent sedimentation and ensure that nutrients are well mixed.
• Monitor water pressure so that it is appropriate for the system and does not cause erosion in the growing medium or damage to the roots.
• Include shut-off valves to be able to isolate sections of the system if maintenance or repairs are necessary.
• Label pipes and connections for easy identification during maintenance or troubleshooting.
• Consider installing a monitoring system to monitor the flow, pressure and composition of nutrient solution in real time.

Step 6: Installation of the Return System

• Install a return channel or pipe at the end of the gutters to collect the nutrient solution that has not been absorbed by the plants.
• Ensure that the return channel have an adequate slope toward the nutrient tank to facilitate gravity flow.
• Install a filter in the return channel to capture any residue before the solution returns to the tank.
• Connect the return channel to the nutrient tank, using secure connections to prevent leaks.
• Verify that the return system does not cause splashes or excessive turbulence in the nutrient tank, which could affect oxygenation and solution mixing.
• Check that the return system is working correctly, ensuring that the nutrient solution flows uninterrupted into the tank.

Practical tips:

• Use transparent pipes for the return system can help easily identify any blockages or sediment buildup.
• Keep the return system accessible to facilitate regular cleaning and maintenance.
• Incorporate a control valve in the return system to manually adjust the return flow if necessary.
• Make sure the nutrient tank has enough capacity to handle the volume of return solution without overflowing.
• Regularly inspect connections and joints of the return system for signs of wear or damage.
• Consider installing a second pump into the nutrient tank to recirculate the solution and keep nutrients and oxygen well distributed.

Step 7: System Test

• Fill the nutrient tank with water to perform an initial test without nutrient solution, to verify the tightness of the system.
• Turn on the pump and observe the flow of water through the gutters and return system to ensure there are no leaks or blockages.
• Adjust the inclination of the gutters if you notice that the water is not flowing correctly or if there are stagnations.
• Check all connection points of the pipes and gutters to ensure that they are well sealed and there are no water leaks.
• Observe the operation of the return system, ensuring that the solution returns to the nutrient tank without problems.
• Check pump and timers (if used) to confirm that they operate according to the established time intervals.
• Evaluate the efficiency of the filter system on the return to verify that there is no accumulation of debris that could cause blockages.
• Make necessary adjustments on water pressure and timer settings to optimize the flow and distribution of the nutrient solution.

Practical tips:

• Perform the test for a long time to ensure that the system is reliable and free of long-term problems.
• Mark with tape or markers any areas that present leaks to facilitate their repair once the system has been emptied.
• Take detailed notes of any adjustments made to have a record of optimal operating conditions.
• Be prepared to make minor adjustments, since it is common that they are needed after the first test.
• If possible, test with plants to observe how they respond to water flow and make adjustments accordingly.
• Consult with an expert or the hydroponics community if persistent or unexpected problems are found during testing.

Step 8: Adjustments and Calibration

• Calibrate pH and EC meters before adding nutrient solution to ensure accurate readings.
• Adjust the nutrient solution at the pH and EC levels recommended for the type of plants to be grown.
• Set the pump timer for appropriate irrigation cycles, based on the water needs of the plants and the capacity of the system.
• Check the inclination of the gutters once again with the nutrient solution circulating, and make any necessary adjustments to ensure a constant flow.
• Control the temperature of the nutrient solution, since extreme temperatures can affect nutrient absorption and plant health.
• Adjust the height and position of the lights (if used indoors) to provide the proper light intensity and spectrum for plant growth.
• Track the system for several days to observe the behavior of the nutrient solution and make fine adjustments to the pump or the inclination of the channels if necessary.
• Document all settings performed to establish a baseline for system operation and facilitate future troubleshooting.

Practical tips:

• Use a record sheet to note adjustments and pH and EC readings daily, which will help understand system dynamics and make proactive adjustments.
• Be patient and make minor adjustments, since drastic changes can destabilize the system and negatively affect the plants.
• Consult guides or nutrient tables specific for the type of plants being grown, since each species has unique requirements.
• Consider using an automated system monitoring and adjusting pH and EC to maintain optimal conditions continuously.
• Check the uniformity of the nutrient solution flow in all gutters to ensure that all plants receive the same amount of nutrients.
• Pay attention to plant signs, such as changes in leaf color or growth rate, which may indicate the need for adjustments to the nutrient solution or growing environment.

Step 9: Plant Placement

• Select the plants or marijuana seeds suitable for the NFT system, taking into account their adult size and nutritional requirements.
• Prepare the culture cubes or sponges that will support the plants, ensuring they are adequately hydrated and pH adjusted.
• Insert plants or seeds in the culture cubes or sponges, placing them in the holes previously made in the gutters.
• Make sure the roots of the plants They have contact with the nutrient solution that flows through the gutters so that they can absorb the nutrients properly.
• Space plants evenly along gutters to prevent competition for light and nutrients and to allow adequate growth.
• Monitor plants for the first few hours and days to make sure they settle properly and show no signs of stress.

Practical tips:

• Start with young plants or seedlings instead of seeds if rapid establishment and initial growth are sought.
• Avoid transplanting plants that are too large, as they may have difficulty adapting to the NFT system and may obstruct the flow of the nutrient solution.
• Use a network or support if growing plants that tend to grow very tall or have heavy fruits, to keep them upright and distribute the weight evenly.
• Observe root development and make adjustments to the position of the plants if necessary to optimize their exposure to the nutrient solution.
• Keep track of growth and plant health to quickly identify any problems and act accordingly.
• Be careful when handling plants to avoid damaging the roots or stems, which could affect their development and productivity.

Step 10: Monitoring and Final Adjustments

• Observe plant growth daily to look for signs of nutritional deficiencies or illness.
• Adjust the nutrient solution as needed, based on plant growth stage and pH and EC readings.
• Check the irrigation system to ensure that all plants receive an even distribution of the nutrient solution.
• Monitor and adjust environmental conditions such as light, temperature and humidity to optimize plant growth.
• Perform pruning and transplants if some plants become too large or begin to shade others.
• Keep detailed records of all the adjustments and observations to better understand the needs of the plants and improve growing practices.
• Schedule regular inspections of the system to prevent and solve problems such as leaks, blockages or equipment failures.

Practical tips:

• Use a growing calendar to schedule maintenance and monitoring tasks.
• Be proactive in solving problems, addressing small problems before they become big ones.
• Consult with other growers or specialized forums in hydroponics for tips and solutions to common problems.
• Experiment with minor adjustments to see how the plants respond and learn from the experience.
• Maintain system cleanliness, since a clean environment is less prone to diseases and pests.
• Be meticulous with hygiene, especially when handling the nutrient solution and plants, to avoid cross contamination.

Maintenance and Management of the NFT System

• Daily inspection of plants for signs of stress, diseases or nutritional deficiencies.
• Daily check of the flow of the nutrient solution and the absence of blockages in the gutters.
• Daily monitoring Check the pH and EC levels in the nutrient solution and adjust if necessary.
• weekly review Check pumps and filters to ensure they are working properly and free of debris.
• Weekly cleaning of gutters to prevent algae and sediment buildup.
• Monthly replacement of the nutrient solution to provide plants with a fresh supply of nutrients.
• Monthly inspection of all electrical and mechanical connections to prevent system failures.
• Monthly deep cleaning of the nutrient tank to prevent the accumulation of salts and other residues.

Troubleshooting common problems and how to avoid them:

• Flooded roots or lack of oxygen: Ensure that the nutrient film is thin enough to allow oxygenation of the roots.
• algae growth: Keep the nutrient tank and gutters covered to minimize light exposure.
• Blockages in gutters: Perform regular cleanings and filter the nutrient solution to remove particles that may cause blockages.
• pH and nutrient imbalances: Monitor and adjust nutrient solution frequently to maintain optimal levels.
• Leaks or spills: Regularly inspect connections and seal any leaks immediately to prevent loss of nutrient solution.
• Pump failures: Have a backup pump and periodically check the main pump to ensure its continued operation.

Practical tips:

• Maintain a maintenance kit including pH and EC meters, calibration solutions, basic tools and common spare parts.
• Record all maintenance activities and observations in a grow journal to track system and plant health.
• Train in the fundamentals of hydroponics to better understand how to manage and maintain the NFT system.
• Establish a maintenance routine and stick to it to prevent problems before they arise.
• Use safe cleaning products for plants and hydroponic systems to avoid contamination of the nutrient solution.