The need reactant molecules to fit precisely into their gaps so all of the negative and positive charges have to line up exactly. Plants are able to change their own cellular pH level to stop or help speed up a certain enzyme reaction. The electrical charges in soil particles are different from those in mixtures with no soil. 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. Too many lights can dry out your plants while too few can have your plants stretching desperately towards the lights. 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. A flow meter and timer regulates the amount of time that the gas is released into the growing environment. Increasing the carbon dioxide in your greenhouse will improve the growth of your plants and it could lead to increased profits for gardeners who sell their plant products. All that is needed for success is careful planning, monitoring and administration of the carbon dioxide gas. A small greenhouse can cost considerably more because you will need to either include a cement floor and drainage system or lay other types of flooring such as gravel before you build the greenhouse itself. Many small greenhouses cost anywhere from $500 to over several thousand dollars, depending on the add-ons you choose. Hydroponics is proven to have several advantages over regular soil gardening. The growth rate on a hydroponic plant is 30 to 50% faster than a soil plant that was grown under the same conditions. The yield of the plant is also greater. There are many reasons for the drastic differences between hydroponic and soil plants.