MH Bulb Life Question

[runway1]

I hear that MH bulbs should be replaced every 10-12 months. The life span is quoted between 8,000 and 16,000 hours!

If I burn mine for 7 hours/day, that's 2555 hours/year - less than 1/3 the advertised life! Why should I replace them? If I should, why are they advertised for such a life?

[AndyH5512]

I believe the answer is because the lights start to lose some of their spectrum. Either that or the LFS and light manufacturers like the extra money from selling lots of bulbs. LOL.

From the first time the bulb is fired up, it loses a minute amount of color. Because it is turned on time after time, the life shortens. The life span the mfg use is based on burning 24 hours a day if I am not mistaken... could be wrong though.

[runway1]

Regardless if it burns continuously or intermintently, hours are hours. So, why the advertised 8k hours of lifespan?

Has anyone noticed any ill effects if burned for more than one year? Just wondering whether I should replace my 11 month old 175W bulbs or not. So far, I see no ill effects in my tank - hence this question.

[Hara]

I am too lazy to type it all out, but here is a thread discussing the "color shift" of my MH bulbs recently. Moral of the story is you really cannot trust your eyes to tell you when bulbs need replacing.

http://www.fantasyreef.com/viewtopic.php?t=422