Does reactor media have a finite useful lifespan?

[Delphinus]

I kind of figured I'd be able to use the stuff indefinitely. But lately it seems to be getting compacted down in my reactor (reactor went online in December for me, so only 3/4 of a year so far). I tried rinsing it, but no amount of rinsing would make the stuff rinse clean (i.e., rinse after rinse of white muddy water). I think it's compacting and it's too hard to for my pump to push water through so the bottom chamber is starting to cavitate.

I went and bought some new media and topped up my reactor. The old media is on the bottom and is quite stark white in colour whereas the new stuff on the top has more of a beige colour (I'm using A.R.M.). To the eye, the particle size is not really any different.

Is my old stuff just spent? Do you have discard media after a while? Is it normal for it to not last a year? I was hoping for at least a year out of the stuff... actually I was hoping to never have to replace it but failing that I was hoping for a yearly schedule. Oh well..