Sodium HID lights emit more red, orange and yellow rays, which, when used alone can cause plants to grow tall and spindly. These lights are used mainly when there is enough natural sunlight present to produce the necessary blue and violet rays needed by plants. Many hydroponic do prefer sodium lamps to metal halide because sodium lights are more energy efficient and often last longer.

Many growers use Metal Halide (MH) for vegetative growth, and High Pressure Sodium (HPS) for budding and flowering. Only rich growers can afford to run the two systems with their own shades and ballasts, independently. Most growers use conversion bulbs, which very conveniently use the corresponding system’s fixtures. So if you have a Metal Halide system, use it for vegging, then put in HPS conversion bulbs into the same system, for flowering.

What often works best in regards to healthier fruits, vegetables and flowers is to use some combination of metal halide and sodium HID lights. The combination provides adequate amounts of both red and blue spectrum colors, both of which are needed for healthy plant growth. Using a combination of the two will provide your hydroponic garden with the best that both have to over. This will translate into healthier plants and a more productive growing season. Lights alone won’t guarantee bumper crops, but work in conjunction with factors such as temperature and nutrition.