How often do you replace your metal halide bulbs?

[troyrb]

How often do you replace your metal halide bulbs? I was wondering because my Coralvue 250w MH bulb is around 8 months old and starting to look dimmer then before. I'm also starting to see small amounts of red slime even though all my levels are normal. Should I be replacing my bulbs more often?

[Geoff]

i replace mine once a year.

where is the cyano showing up? cyano grows where there is extra nutrients. if no nutrients than no cyano, regardless of the light spectrum.

G~

[Junkzoo]

Change my two bulbs yearly also, but change one six month's b4 the other,as not to shock the tank w/ the new lights,,,,,

[Casey]

once a year.

[VWD]

I think If you do them once a year You will be safe. I like the idea of one then the other 6 months later. I never done it like that but may be a little more easy on the tank.