Average life of Metal Halide bulbs?

[dvb]

What is the average life of metal halide bulbs before they burn out?

How long before you really need to replace them?

I have a Hamilton 250w 10k that burned out after a month. I have returned it and they are sending me a new one for free, but it made me start thinking about the expected lifetime.

 

[ErikS]

They generally last a long time, probably over two years in regular use. The problem for reefkeepers is a spectrum shift after a year to 18 months. This makes the bulbs unsuitable for our needs. Most folks change the bulbs once a year. Also, most change them one at a time so as not to shock the corals with the change.

 

[Anonymous]

Burn out is a long time after the spectral shift takes place. The life depends on the color temp or Kelvin rating. The higher the K the shorter the useful life. The 20KK seem to go about 6-8 months.