Even in the growing era of LED Grow Light technology, many hydroponic growers prefer the gas-charged high-pressure sodium (HPS) or metal halide (MH) grow light systems, especially for larger commercial applications. The intensity, broad-spectrum and light consistencies make HPS or MH lighting suitable throughout the entire plant cycle. This means that the same grow light system can be used from the cloning or seedling stage through the plant’s maturity and harvest. The main difference between these two types of grow lights is the spectrum they produce. MH grow lights produce a blue spectrum, perfect for vegetative growth, whereas HPS grow lights emit a red spectrum, ideal for flowering or blooming.