I used to get the same results with the red tumbling media. I just use reptile bedding from a pet store now. Throw a cap full or so of liquid car wax in with it. Get real clean which is what you want but not quite as highly polished unless you leave it a long time, but you also don't get the red.
The sonic cleaner is the ticket for those places you can't get at like the inside, but it will also knock off the shine some.
If you sonic clean first all will be clean, when you tumble you'll get the red, kind of a vicious circle.
I don't use Sonic much, don't have a large one, just a little one for jewelry. I don't like dealing with the wet and drying.
Tumbler alone works well enough for me.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."