Hydroponic System Types

The systems described below are the six most common methods (Wick System, Water Culture, Drip System, Flood and Drain, NFT and Aeroponics) for growing plants hydroponically, indoors and out.

Wick System

The wick system is a form of passive hydroponics (no moving parts), making it one of the most simple hydroponic growing methods.  Plants are grown in an inert medium, such as perlite or coconut husk (coir) that absorbs or “wicks” nutrient solution from a reservoir, providing a constant supply of water and food to the plant’s roots. Because of their simplicity and lack of active parts, wick systems are protected against pump and power failure.

A Soda Bottle Planter is a simple example of a wick system.

Passive Wick System

Water Culture

Deep Water Culture System
Diagram of a Raft System with an Air Stone

Water culture systems are the simplest form of active hydroponics. They have a long history, dating back to hanging gardens of Babylon. Deep water systems were also used by the Aztecs, who grew crops on floating rafts on lakes.

Plant roots grow directly into the system’s reservoir. Roots are supplied oxygen by an air pump. Water culture systems can be built using repurposed glass mason jars, or plastic buckets/tubs as the reservoir. The plant is suspended from the lid in a net pot, allowing roots to grow through the holes into the water below.

In larger, commercial-scale systems, several plants are placed in a sheet of buoyant material that floats on nutrient solution like a raft. Water is generally held in a separate, larger reservoir and pumped up to the floating grow bed, then drained back down to the reservoir in a constant cycle. These systems is the least susceptible to pump and power failure.

Drip System

A drip system is another example of active hydroponics. Drip systems evolved from drip irrigation technology created for conventional soil agriculture. Plants are either grown in a substrate or suspended directly in water (like water culture systems). Nutrient solution is dripped onto the base of each plant stem, hydrating upper parts of the root system. The excess nutrient solution that isn’t used by the plant can be collected back into a reservoir for reuse: this is called a recirculating system.

Recycling excess nutrients is not always necessary. Drip systems can also be built so that excess nutrients drain out directly onto a soil garden underneath (drain-to-waste system). The downside to this, especially when using non-organic fertilizer, is that it is a form of agricultural runoff. Another drawback to drip systems is clogged nozzles and overheated drip lines. These issues can be abated by using different dripping techniques.

There are three major types of drip techniques: airlift, timber-controlled pump, and standard regulating dripper.

  • An airlift uses the rising action of air bubbles to carry water up a tube and out onto the top of a root system. It creates a drip-like effect that is very energy efficient.
  • Water pump cycling involves putting a water pump on a timer. When the pump is turned on, unobstructed water lines temporarily feed the plants with a continuous flow of nutrient solution until the pump turns off again.
  • A standard dripper regulates water flow to achieve a set amount of gallons per hour. Standard drippers are prone to clogging when used in hydroponic systems because mineral-based nutrients can leave salt residue that obstruct small spaces.

Many commercial tomato growers use a drip system in their greenhouses. Drip systems are also effective for almost any type of plant, as they allow for full-root nutrient coverage.

A Bato/Dutch Bucket Drip System
Drip System

Flood and Drain (Ebb and Flow)

Flood and Drain Germination System
Diagram of a Flood and Drain System

Flood and Drain is particularly effective for its low water usage and speedy plant development. This method was developed during World War II to grow tomatoes and lettuces for American troops in the Pacific, and was also one of the first documented uses of volcanic glass and rocks as a growing medium.

Plants are sown directly in a tray filled with growing medium. At intervals regulated by a timer, a water pump fills the tray with nutrient solution from a separate reservoir, saturating the growing medium and plant roots. The water begins to recirculate back into the reservoir through a one-way overflow valve. When the timer turns the pump off, the tray drains completely, providing the roots with oxygen.

This technique is used in our Germination System.

Nutrient Film Technique (NFT)

In NFT, or continuous-flow solution culture, plants are suspended and the roots grow down into a shallow, constant stream of nutrient solution, which is pumped into the channels from a separate reservoir. The parts of the roots that are not submerged in the water absorb oxygen for the plant. The channel containing the plants is built at an angle in order to use gravity to move the solution past the roots. Nutrient solution is then recycled back into the main reservoir. NFT systems scale well, as one central reservoir can hydrate several channels of plants. Unfortunately, this technique is very vulnerable in the event of pump and power failure.

NFT systems are most widely used for growing leafy greens and herbs such as lettuce and basil. The technology for NFT systems was developed primarily in the 1970s and 80s.

Nutrient Film Technique System on a Rooftop
Side View of an NFT Channel


Leaf Lift Systems Aeroponics System
Diagram of an Aeroponics System

In an aeroponic system, plant roots are suspended in air and saturated with a constant mist of nutrient solution. An advantage to using aeroponics is that suspended plants receive 100% of the available oxygen at the root zone, as well as at the stems and leaves, which accelerates plant growth. NASA has been researching aeroponic techniques as a possible method for growing food in space, since a nutrient solution mist is more manageable than liquid in a zero-gravity environment.

Leaf Lift Systems has discovered that aeroponics speeds plant metabolism in young plants, resulting in a ~25% increased growth rate in experimentation settings when used in appropriate high-pressure aeroponic environments. This makes aeroponics particularly effective for germination and seedling development as well as cloning applications.

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