Deep water culture

[2] DWC, along with nutrient film technique (NFT), and aggregate culture, is considered to be one of the most common hydroponic systems used today.

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[4] The large volume of water helps mitigate rapid changes in temperature, pH, electrical conductivity (EC), and nutrient solution composition.

A grower utilizing a DWC system has to modify the environment as to provide the proper conditions for optimal growth.

This requires special attention to specific parameters which are described below in more detail (oxygen, temperature, pH and nutrient concentration).

As in other methods, soils and soilless media can assist in acting as a buffer for potentially harmful agents like disease or water quality concerns.

Plants require oxygen to carry out the process of root respiration that is imperative for healthy growth, such as the uptake of fertilizer salts.

The primary disadvantage of RDWC is that disease can spread quickly in these systems which can facilitate the transfer of pathogens from one reservoir to another.

FRT systems utilize floating rafts in ponds that allow for the roots of the plants to be suspended in a nutrient (fertilizer) solution.

[14] Commercial systems are typically constructed in greenhouses, though they can be installed outdoors, under other forms of protection, or completely indoors.

For head lettuce and other large-leaf greens, seedlings are typically germinated in soilless media cells (such as rockwool or coconut coir) and then transplanted into the floating rafts, which are usually made from low-density plastics such as food-grade polystyrene.

For baby leaf lettuce, seeds are often sown and germinated in higher densities in specialized rafts made to contain soilless media.

[15] One advantage that DWC systems have over other forms of hydroponics is that plants may be re-spaced during the growth period, optimizing the growing area in regard to canopy cover and light-use.

[16] The rafts are generally cleaned after each harvest by scrubbing to remove organic matter and applying bleach or other sanitizing agents to reduce to presence of diseases.

In commercial systems, this process is often assisted by automation, where rafts are sent into a machine via conveyor belt, on which they are successively washed, sanitized, and dried.