How often do you change your VHO light bulbs?

[fish head]

After how many months should URI VHO bulbs be changed? I have heard various opinions.

 

[jacksonpt]

Probably depends on how long you run them. Granted, I have NO bulbs, but I try to replace them every 6 months just to be on the safe side. I run my actinic bulb for about 15 hours each day, and my full spectrum bubls for about 10 hours each day.

 

[jimi]

Every 6 to 8 months.

 

[up north hermit]

My research has yielded the following results: old tar and coil ballast = change bulbs every 6-8 months. New electronic ballasts = change every 12 months.
I have the URI bulbs and run my lights 10 hours a day. I have four bulbs and change one bulb every three weeks starting in the 11th month.
HTH
Hermit