The wick system is one of the easiest and most basic of all hydroponic systems. It has no moving parts and requires a reservoir for the hydroponic solution, a grow tray for supporting the plants, and wicks. Common wicks are cotton or nylon rope. While inexpensive, wick systems do not work well for large plants that require large amounts of water, such as tomatoes.
With the wick system, the entire grow tray is full of growing medium. In other systems, trays often use mesh pots to contain the media, allowing it to absorb water and nutrients as the water levels ebb and flow. With the wick system, the growing media must provide capillary action for wicking without compacting. Soilless mixes, perlite or vermiculite are good choices.
The wick system keeps the roots wet continually. This means the nutrient solution requires aeration, often accomplished using an aquarium pump and air stone. Aerating the solution provides the oxygen the roots would normally absorb during the dry cycles of other hydroponic systems.
Wicks transport the nutrient from the reservoir to the growing tray. Cotton rope is inexpensive and effective, but rots and molds over time. Nylon rope is not subject to either rotting or molding. Systems generally require one wick per plant, with the top of the wick near the rootball.