2 of my cats will be 4 years old in Dec, and the other is 2 years old.

They have always been fine before, except Tage, his pee got that very over whelming ammonia smell when he was eating Pro Plan Dry. I removed him from that food, and everything went back to normal.

So it's not an issue with the litter I use, or deoterizers etc, it's a problem with one of my cats, I need to figure it out so I can fix it.

Even after they use a fresh clean box just one day I can't stand it when I scoop it, let alone a week!

I can't think of anything which has changed in the past 1 1/2 - 2 weeks however. Perhaps they will benifit from more wet food in their diet right now then dry, to make up for the lost moister.