High Intensity Discharge Grow Lamp (HID)

Last Updated: February 21, 2017

Definition - What does High Intensity Discharge Grow Lamp (HID) mean?

High intensity discharge lamps, otherwise known as HID lamps, are electrical gas-discharged lamps that produce high-intensity light through an electric arc. In horticulture, HIDs are commonly used for hydroponic or other forms of indoor gardening.

MaximumYield explains High Intensity Discharge Grow Lamp (HID)

High intensity discharge grow lights produce an electric arc between tungsten electrodes housed inside a translucent tube. This electric charge excites gas molecules, which, as a result, produces a high-intensity light.

High-intensity discharge lamps are considered a type of arc lamp. In earlier designs, mercury was the gas of choice. Today, radioactive gases such krypton-85 are more commonly used and produce the same effect.

HIDs make excellent grow lights because of the intensity of the UV rays and through the light produced. This intense light helps with the photosynthesis process for plants grown indoors.

Newly installed HID lamps produce far more usable light that fluorescent or incandescent lamps since more of their radiation is visible light compared to infrared. Interestingly, the lumen output of HID lighting deteriorates over 10,000 burning hours, by as much as 70%.

So, unlike fluorescent lighting and light-emitting diodes (LEDs), HIDs will lose their effectiveness over time. For this reason, the number of hours that the lamp is used as a grow light must be properly monitored in order to gauge replacement.

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