HID (High Intensity Discharge) bulbs has become the standard light in hydroponics due to its ability to provide proper amount of spectrum for an indoor garden. While they are more expensive than fluorescent bulbs and emit more heat, this type of light is generally the perfect substitute for sunlight in hydroponic gardening. There are two kinds of HID bulbs that you can use depending on the growth stage of your plants. You can use a MH (metal halide) bulbs in the vegetative days of your plants then you can switch to a HPS (high pressure sodium) light once your plants reach the flowering or fruiting stage. The great news is, Hydrogalaxy has both kinds of HID bulbs in our store. Enjoy shopping!