INTRO to CEA |
Hydroponics |
2026 |
Foundations 1
Lesson 3: Hydroponic System Types
Deep Water Culture (DWC)
Deep Water Culture (DWC) is a hydroponic method in which plants float on rafts or other supports above a nutrient‑rich water reservoir, and their roots hang directly into the solution. An air stone or similar oxygenation device keeps the water highly oxygenated so roots can absorb nutrients while staying in continuous contact with water. DWC is simple to build and maintain, and is especially effective for fast‑growing leafy greens and herbs.
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Nutrient Film Technique (NFT)
In Nutrient Film Technique (NFT), a thin, continuous film of nutrient solution flows through shallow sloped channels or gutters, while plant roots dangle into the stream. The system uses a pump and reservoir to recirculate the solution, and the shallow flow exposes roots to both nutrients and air, promoting rapid growth. NFT is water‑efficient and works well for leafy greens but requires careful slope and flow‑rate management to avoid drying or waterlogging.
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Ebb and Flow (Flood and Drain)
Ebb and flow (also called flood and drain) systems periodically flood planting trays with nutrient solution from a reservoir, then let the solution drain back out. This cycle delivers nutrients while exposing roots to air during the dry phase, which helps prevent root‑zone oxygen depletion. The system usually consists of trays, a reservoir, a pump, and a timer, and it can use a variety of growing media such as expanded clay pellets, coco coir, or rockwool.
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Drip systems and media‑based systems
Drip hydroponic systems deliver nutrient solution to each plant through small emitters on a network of tubing, often into a growing medium such as coco coir, perlite, or rockwool. The medium holds the plant upright and buffers moisture and nutrients, while excess solution drains away or is recirculated. Drip systems are flexible and scalable, and are commonly used for larger‑rooted crops like tomatoes, peppers, and cucumbers.
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Vertical farming applications
Vertical farming cultivates plants in stacked layers or on vertical surfaces, often indoors, to maximize space and resource efficiency. Hydroponic systems such as NFT, drip, and media‑based setups are frequently incorporated into vertical farms along with controlled‑environment technologies like LED lighting, climate control, and closed‑loop water recycling. This approach is especially useful in urban areas where land is limited and can reduce food‑miles by locating production close to consumers.
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Microgreens
Microgreens are nutrient‑dense, fast‑grown seedlings harvested in 7–21 days, usually indoors in shallow trays with controlled light, temperature, and watering.
- Selecting appropriate seed types and deciding between soil, compost, coco coir, or mat‑based media.
- Tray preparation, sowing density, and pre‑moistening the growing medium to ensure even germination.
- Using a blackout or “chuppah” phase during germination, then transitioning to bright light (natural or LED) for greening.
- Watering from the bottom to avoid over‑saturating the surface and reduce mold risk, adjusting as trays dry out.
- Harvesting at the cotyledon or early‑true‑leaf stage, just above the base of the stem, and managing post‑harvest storage and food safety.
- Lesson (forthcoming)
Study guide: Key concepts and study tips
- Define each of the five main hydroponic system types (DWC, NFT, ebb and flow, drip, vertical applications).
- Explain how root‑zone oxygen is supplied (or managed) in each system.
- Describe how water and nutrients are delivered and recirculated in NFT and drip systems.
- Describe the role of growing media in media‑based systems and vertical farms.
- Explain why vertical farming is particularly suited to urban environments.
Active‑study suggestions
- Sketch a simple labeled diagram for each system showing the reservoir, pump/timer, and root zone.
- For each system, write 2–3 bullet points in your own words summarizing how it works and what crops it suits best.
Common misconceptions
- NFT does not use “deep water”; the film is very shallow and flows continuously, not statically.
- Drip systems are usually media‑based and not purely “water only,” unlike DWC.
Quiz: Check your understanding
- Which hydroponic system keeps plant roots suspended in a constantly aerated nutrient solution?
- Which system uses a thin, continuous stream of nutrient solution flowing through sloped channels?
- What is the main mechanism that provides oxygen to roots in an ebb‑and‑flow setup?
- In which system are plants grown in a growing medium and irrigated with individual emitters?
- Which system is best suited for large‑rooted fruiting crops such as tomatoes?
- What key feature distinguishes NFT from DWC?
- Which system periodically floods the root zone and then drains it back to the reservoir?
- Which of the following is a primary advantage of vertical farming in urban areas?
- In DWC, what is most critical to prevent root suffocation?
- Which of the following is a common growing medium used in media‑based drip systems?
- Which system is typically considered the simplest to build for beginners?
- What happens to the nutrient solution between flood cycles in an ebb‑and‑flow system?
- Which system is most space‑efficient for growing leafy greens in a small footprint?
- Which of the following is NOT a typical component of a basic NFT setup?
- What is the main purpose of the growing medium in a drip system?
- Which system relies heavily on gravity and careful slope design to move nutrient solution?
- What makes vertical farming attractive from a sustainability and logistics standpoint?
- Which type of system is most likely to use expanded clay pellets or coco coir as the primary support for plants?
- What is a key maintenance task common to DWC systems?
- Which hydroponic technique is frequently combined with vertical‑stacked layers in indoor farms?
Options for each item:
- A. Deep Water Culture (DWC)
- B. Nutrient Film Technique (NFT)
- C. Ebb and flow (flood and drain)
- D. Drip and media‑based systems
Answer key
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