When to change old hps bulbs for new ones

I've been buying new hps and mh bulbs at the start of every new season after using the old ones for three grows (9 months more or less). I've done this because I remember reading it somewhere, but I was wondering if this is the way to go. Also, where to recycle the old bulbs?
Thanks

bubbascruggs said:

I've been buying new hps and mh bulbs at the start of every new season after using the old ones for three grows (9 months more or less). I've done this because I remember reading it somewhere, but I was wondering if this is the way to go. Also, where to recycle the old bulbs?
Thanks

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I think we read the same thing! LOL! I just changed mine out after the third grow. I don't have to recycle mine because I'll use the old one as a back up. If the new one goes toast, I can put the older bulb in until I can get a replacement bulb.

Seriously though, I do remember an article showing the degradation of light intensity as the bulbs got older.