How often do you change your MH bulbs?

I am just curious
How often do you change your MH bulbs? :-[ so I can get an idea
How often I should be changing My MH bulbs :

 

Once a year for me.

 

Ditto. Maybe a little before. I always right the month I buy it on the box and save it for reference.

 

My plan is for every 12 months as well

 

So it seems 12 months is pretty much agreed on then so far!! So I still have around 5 months left if I fallow the same schedule. ;D
Anybody have a different schedule? :-/ or any info on why 1 year is the magic number? Like what the average life of a MH bulb is before it's spectrum changes to an unacceptable Range? ........................... John

 

I have read 2 - 3 years (Calfo said on checking PAR at two years, there was very little decrease) altho, historically , I change mine once per year as well

 

Well, I've had MH for less than a year, and I've changed the bulbs twice already! Once because I wanted a bluer bulb that the 10k, and the second time because I switched from mogul base to double-ended. I hope to make these last at least a year, though!

P.S. If anybody wants to buy some 250W bulbs with lots of life left in them, I'll sell them cheap!

 

Thank's all for your input.
I have been looking on Ebay and came across these bulbs, Has anyone ever used them or even herd of them? John

http://cgi.ebay.com/400-W-20-000-k-...704402397QQcategoryZ46314QQrdZ1QQcmdZViewItem

 

Some cheaper brands (no names mentioned) only last 6 months until their peak PAR drops considerably.

 

Without asking you to recommending a specific brand bulb I will just ask, What Bulbs do you use Gresham? ;D John