tank lighting lifespan?

[karak40]

How long is the usual time to replace your Power Compact light bilbs? Do they loose there lighting abilities after a certain point of time. My LFS told me that my caulerpa is not growing in my refugium because I need to replace my bulb even though the light is still working? is this true? Thanks

 

[markeo99]

it is true they lose par value a pc is good for 6 or so months
mh 8ish and t5's a year or a little better