Bulb Life

[twiddledog]

I am curious how often people change their bulbs. I have T5 and MH. I have read and heard 9 months, but is that really true or just a marketing ploy.
Like auto shops say to change your oil every 3,000 miles but you can really go alot longer.
Is there a real degredation over 9 months? Would you see it with coral health and growth? Or, can you really get about 12 - 18 months without any real degredation?

 

[pallobi]

I use my t5s for 8 to.9 months tops... maybe they will last longer, and maybe its a marketing ploy, i cant say for sure, but its what im comfortable with... i like fresh bulbs...

 

[labnjab]

I changed our MH bulbs every 9-10 months, any longer then that and I would start getting really nasty algae. Sometimes it was sooner if the algae came early. Its half the reason we switched to LED, replacing 3 MH bulbs at the same time gets expensive, lol

 

[KSC]

It really depends on your particular bulb and fixture. It would also depend on your definition of "last". For example, in my t5 fixture, the bulbs lose about 20% of their output in 6 months. In an uncooled fixture, or one that overdrives the bulbs, I've read that this 20% loss can occur in 4 months. Mh bulbs tend to lose some output initially, but then level off and can be used for a year or two. I think the notion that "old" bulbs cause algae is an old reefers tale. New bulbs that have greater intensity will grow algae just as fast as old bulbs that have lost some intensity. There's some good info regarding MH life here:

http://reefkeeping.com/issues/2007-04/ac/index.php
http://www.advancedaquarist.com/2008/7/aafeature1