• The University of Arizona's College of Agriculture and Life Sciences describes hydroponics as a system that grows plants in nutrient-rich water or fertilizer. A liquid hydroponic system uses water to support plants, while an aggregate system uses an artificial growing material for support, such as sand, sawdust, gravel, peat or sand. In an open hydroponic system, the nutrient solution interacts with plant roots without being recycled. In a closed hydroponic system, the nutrient solution provides constant nourishment to plant roots through a process that pumps it through the system continuously.
  
  

Fungus Gnats

• According to Dr. Lynette Morgan of Simply Hydroponics and Organics On-line, fungus gnats are tiny, dark flies are known for their long legs and unusual wings. Also known as sciarids or sciarid flies, fungus gnats reside near plants, growing materials and leaves. At maturity, fungus gnats can measure between 0.06 and 0.125 inches long. Fungus gnats thrive on the high moisture levels characteristic of hydroponic systems, and lay eggs inside the plant's potting mix. The eggs hatch, sending clear or white larvae to feast on fungi or dead organic matter inside the growing material. If they are not controlled, a fungus gnat's larvae can spread pathogens inside the container. When pathogens attack the plant's roots, the plant cannot receive the nutrients suspended in the hydroponic solution. Consequently, the plant will become deficient in nutrients and die.
  
  

Water Leakage

• Hydroponic systems rely on pumps to release a nutrient-rich solution into the water. Pumps operating at higher pressure possess greater risk of leaking than systems using low pressure. Typically, leaks occur when stab fittings and emitters shift out of place. Sometimes leaks result from root growth that causes water to accumulate and overflow when tubes are not big enough to contain the water.
  
  

Algae Growth

• Algae is recognized by its color---green, brown, red or black---as well as by an earthy or musty scent that results from deteriorating plant nutrients. When it develops in the hydroponic solution, it can obstruct hydroponic drippers and emitters and attract gnats, larvae and nematodes. Once established, algae absorbs nutrients from the solution and blooms. When the algae dies, it decomposes, extracting oxygen from the hydroponic solution, which causes the plant's roots to die, suffocating because there is no oxygen in the water. Once dead, the plant's roots become susceptible to damage-causing pathogens, like Pythium. To prevent algae from growing inside a hydroponic system, avoid exposing the plant's nutrient solution to light. Place plastic covers over channels, gullies and media beds. If the algae growth is too heavy or extensive, remove the plant and grow it in a clean hydroponic system.
  
  

Clogged Systems

• Hydroponic systems that use drips and sprays, such as aeroponics, commonly suffer from clogs. Because they operate using high pressure, drip-and-spray hydroponic systems push nutrient-rich solution through tiny holes. Although filters reduce the chance that clogs will develop inside drip-and-spray systems, installing them will not remove the problem completely. Routinely inspect nozzles and drip heads, replacing ones that no longer function effectively.
  
  

Maintenance

• Expect to monitor the system regularly. Inspect the nutrient solution a minimum of once every day. Drip systems require more monitoring; check them two or three times every day, looking for clogs obstructing the emitters. When growing plants in a material that drains quickly, check them often to ensure that an adequate supply of nutrient solution is available. Otherwise, the plant will die after a few hours of solution.