powercompact lighting

[julie]

I have the powercompact/metal halide lighting on my 200gallon
tank. I was wondering how often should the bulbs be changed?

 

[cliffrouse11bas]

From what I hear ever year...

 

[finland]

You should change them about once a year, but you might want to change them at intervals. If you replace them all at once, the tank inhabitants will have to be acclimated to the new lights. Maybe just reduce the photo-period for a couple weeks, gradually increasing time bacvk to what you have it right now.