HPS Life and Lumen Maintenance

Marijuana Horticulture

by Jorge Cervantes

High pressure sodium lamps have the longest life and best lumen maintenance of all HIDs. Eventually, the sodium bleeds out through the arc tube. Over a long period of daily use, the sodium to mercury ratio changes, causing the voltage in the arc to rise. Finally, the arc tube’s operating voltage will rise higher than the ballast is able to sustain.

At this point, the lamp will start, warm up to full intensity, and go out. This sequence is then repeated over and over, signaling the end of the lamp’s life. The life of a 1000-watt HP sodium lamp will be about 24,000 hours, or five years, operating at 12 hours per day. Replace HPS bubs after 18 to 24 months to keep the garden bright.