I've never used NitraZorb, but I've seen the packets.
Could you be more specific about "blurry", and how long it's been that way?
Also, what kind of filter do you have?
If the "blurry" is just gunk floating around, it may be as simple as the fact that you moved the filter media aorund while the filter was running (I do that all the time, it seems, and slap myself for it).