All plants respond differently to light depending on the intensity, wavelength and duration it receives. Many hydroponic gardeners have to experiment with different lighting to achieve the best environment for the plants that they are growing. Air pollution can affect the growth of your greenhouse plants and must be monitored if you live in a large city. Though the pesticides used in hydroponics do not run-off and pollute the surrounding environment like the pesticides used on traditional fields, they are still on the plants themselves. The field of hydroponics is filled with promise, and much research is being devoted to solving the concerns that currently stop more farmers from going hydroponic. These systems try not to use pumps and may rely on the use of a wicking agent to draw nutrients to the roots. Media based systems use some form of growing medium. Some of the more popular media based systems include ebb and flow system; run to waste system, drip feed system, and bottom feed system. Water culture systems do not use medium. Using enemy insects is a safe and poison free way of controlling spider mites. Natural enemies will feast on the spider mites until there aren’t enough for the predator to survive, then they will die off or leave in search of more food. Releasing predator insects into your hydroponics garden infestations of spider mites can be eliminated or, they can be avoided. It uses much less water than conventional gardening and does not erode the soil or add toxins to the environment. Soluble nutrient formulas are re-circulated and used by the plants’ roots, which helps eliminate environmental waste. As many gardeners today are choosing to grow organically, organic crop cultivation in hydroponics has become very popular. The energy saving poly greenhouse covers, the PVC pipe used in the feed systems, and the nutrient injector pumps & reservoir tanks were all made of types of plastic not available prior to the 1970s. As both small and large hydroponic farms were established in the late 1970s, it was proven that hydroponic culture could produce premium produce and be a profitable venture.