Does GFO have an expiry date?

[zhasan]

I just used some Barrier Reef GFO media in my tank last month. Its at least 3 years old. It worked well but my phosphates levels creeped back up in about a month. I think the increase is due to the high volume of phosphates in my tank and use of minimal amount of media in a tank with very high levels of phosphates.

So, IMO, it does not have a shelf life as long as it stays dry.