Last night I popped the lid off my tumbler to sift out some 45 Colt brass. It had been tumbled for about 7 hours and wasn't particularly dirty brass. Just once fired American Eagle loads. Despite the long tumbling, the cases still had some scorch marks around the mouths, and had some dark streaks on them. I decided media is cheap enough that I don't care. I replaced it. I think at this point I've only tumbled about 6000 cases in it. Whatever...........
I have another 4000 to 5000 cases to clean and then I'll have it all polished up. Once that happens I'm going to tumble brass as soon as it's been shot so I maintain a "clean inventory" rather than piles of dirty stuff. I'm guessing at that point, media will be lasting me a lot longer.
I've been running my tumbler for about 5 hours a day, four or five days a week, for the last three weeks.
I'm getting in the habit of running the vacuum through my loading room whenever I pour media from sifter to tumbler and back. It's probably overly careful, but it isn't practical for me to keep my cats out of the reloading room. Their cat boxes are on the other side of the attic. My concern has been they walk through dust on the carpet, clean their paws, and then they are eating lead dust. I shoot jacketed bullets pretty exclusively, but I still want to be cautious.
The benefit to having two ninja/acrobat children in the house that have free access to every room is that they sure do inspire you to stay clean and organized. the down side is that I have to have child safety locks on all my cabinets, and I find puke in places I'd rather not.