Hydroponic gardening is one of the most popular methods for plant production. This form allows people with no land, or land unsuitable for plant growth, to produce food and flowers with ease. As you go about building your hydroponics system you will will want to invest in excellent grow lights. Many gardeners choose HID, or high intensity discharge, grow lamps because they most closely resemble natural sunlight, and this is conducive to excellent plant growth in an indoor growing situation. However, not all grow lights are created equal.

There are five types of HID lights, and they include mercury vapor, low-pressure sodium, xenon short-arc lamps, metal halide and high-pressure sodium. Metal halide and high-pressure sodium make great hydroponic lights.

A metal halide grow light produces a light in the blue spectrum, which is useful to young plants to help them attain maturity. For this type of light to work, electricity flows through a mix of metal halides and mercury, as well as argon gas. The metal halides have an affect on the color of light the lamp produces as well as the strength of the light. Metal halide lights are made up of a metal base and a bulb made out of glass. Inside the lamp you will find wires, a quartz arc tube, tungsten electrodes, metals and gas. In order for a metal halide lamp to function properly, you must use an electrical ballast. The ballast controls the flow of electricity to the light bulb, and metal halide bulbs, when used with specially designed electrical ballasts, allow for dimming of the light as well. Metal halides offer a great deal of control over the color temperature, or the color of the light, produced, which is why hydroponic gardeners like these lights.

A sodium vapor light, on the other hand, uses sodium to produce light in the red spectrum. Unlike the metal halide lamp, the high pressure sodium light uses an alumina arc tube. Alumina makes use of a diffused aluminum oxide, which is necessary because of the great deal of chemical activity that occurs with a high pressure sodium arc within the bulb. A high-pressure sodium lamp also must use a ballast to control the flow of electricity to the light, much as it does in the metal halide application.

Indoor gardeners enjoy using both of these types of bulbs because they give off a very intense light, which is needed by plants to thrive. Blue spectrum light of metal halide bulbs is beneficial when plants are young to enhance growth, while red spectrum light provided by high-pressure sodium lamps helps plants produce flowers and fruit. Select both lamps to enhance your plants' entire lifetime photosynthesis needs.