Hydroponic plants are entirely water based which makes it possible to fully automate the hydroponics system. Specially formulated hydroponic fertilizer mixtures are required and should be tested after dilution to ensure a pH level of between five and six. This nutrient solution should be changed every two weeks and in between changes should be checked so the volume is kept level by adding more water only and not additional formula. 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. Signs of air pollution include spotting or twisting of the plant’s leaves, flower and bud fall off, and unusual discolorations as well as poor growth can signal a problem. Plants can be placed much more closely together than in traditional fields; as many as four times as many plants can be grown in the space using hydroponic techniques as opposed to traditional methods. Secondly, hydroponics eliminates many of the problems associated with traditional farming that leads to sickly, damaged, or wasted crops. Once the batch has stopped bubbling the fermentation process has ceased and another batch will need to be made in order to continue the production of carbon dioxide. The use of decomposing organic matter is rarely used indoors because of the odor and it is unsanitary because of the bugs it attracts. It can be used outdoors in a greenhouse but the bug problem and their potential diseases need to be addressed in order to save your plants from their adverse effects. Usually, natural sunlight is used, but during the shorter and darker days of winter, many hydroponic gardeners use artificial lights to increase the intensity of light or to expand the daylight length. Different types of artificial lighting are selected for specific plant varieties and optimum plant growth characteristics. Commercial crop growers are turning to soil less cultivation more and more. The speed of growth combined with the control over the growing environment means higher quality crops. The worry over soil born diseases and pests are greatly reduced, plus weeding is a thing of the past. For commercial growers, rapid harvest and higher yields are great reasons to grow hydroponically.