Changing MH bulbs

[lavoisier]

I have read conflicting advice over the years on how often to change MH bulbs. I have 3 400w MH fixtures. Do I have to change them every 6 months or can they provide quality light for 2 years? Thanks for your response.

 

[Sea MunnKey]

Majority of MH bulbs have at least a 1 year use of intensity.

 

[Captain Quint]

I never ran over 1-year with some brands being more of a 6-month bulb.

When they start to diminish their optimal life your system will develop some hair algae which is a pretty good indicator IMHO.

 

[jda]

Are you over driving them? If not, then they will last a year. Some will last even longer, but this is brand specific.

Which ones do you have? What ballasts are you using with them?