Vho's...when to change??

[Bsmith_SigEp]

I have VHO bulbs in my tank...2 normal white ones and 2 blue actinic bulbs...4 total....how do you know when you need to change to newer bulbs....these still seem bright as ever and no issues with them..but they are at least 2 years old if not 3...not quite sure on the time......But would this be a reason of why i cant get rid of the purple-ish blue mushrooms in the tank on my rocks?

 

[Reef264]

6-7 Months is about the normal rate.

 

[Rudolph]

I have also heard that it can depend on your fixture and every 9-12 months. I have four bulbs as well and I like the idea of changing one of the four bulbs every 3 months. That way you are not changing them all at one time and you have more consistent lighting levels throughout the year.