"It seems as though more people care about the media than the tumblers themselves." James (reloading apprentice)
That seems to be true. Actually many, especially aprentices, tend to agonize over media and polish far too much.
Media - use cob or nut. Not much difference between the two and what there is doen't make any difference. How often to change media? Hardly ever. As long as it's still in kernels it will work fine. Finely ground cob or nut from a pet supply shop or a farming "seed" store is much less costly than the repackaged reloader branded stuff.
Add a few bits of a loose weave material, old dryer sheets cut into 2" squares are popular, occcasionally. It will trap powdered "dirt" (actually, it's mostly dried polish, fine media and case crap) in the loose fibers so you can toss it out.
Polish - No matter the label, all metal polishes are pretty much the same. Cheap auto polish works as well as the most expensive reloading branded stuff, probably the same actually.
Avoid polishes that include ammonia; like Brasso. Nu-Finish auto polish is easy to find and inexpensive too. There is absoulutly no value to gilttering brass so don't over apply the polish, a coupld of caps full the first time and another cap full after maybe 8-10 loads is plenty. Too much only discolors the media and makes a lot of dust. Tumbling a long time does little good and brass oxidizes fairly fast so a glitter finish only lasts a couple of days anyway.
Thoughts:
A couple ounces of mineral spirits may be added to the media to help it cut surface crud from the brass. It's especially helpful for pistol cases which tend to have a lot of blow back on the sides. Mineral spirits evaporates pretty fast so you would need to add some each day you process a batch or two.
DO NOT add liquid polish, etc, to the media immediately before beginning tumbling. Allow it to churn and mix until you see NO CLUMPS before adding cases. Otherwise, you will have the clumps impacted in cases!
Don't worry about the "lead dust" too much. There is very little lead, if any, in the media dust anyway and if you don't lick your fingers clean after tumbling you will be fine.
Is your tumbler noisy? Experiment. Tighten or loosed the nuts holding the bowl and lid in place. Add more media or fewer cases. You will soon learn how to reduce the noise to a minimum.
Make sure your tumbelr has good air circulation to cool the motor. How? Check the temp of the sides of the base; if it's hot you ain't got good air flow! Common culprit is sitting the tumbler on carpet to deaden the noise. Use a pad of newspapers or cardboard instead. I bored a series of 1/2" holes around the base enclosure on my Lyman to help it run cool - worked fine!
If your new tumbler doesn't have a power switch buy a simple "line switch" from Lowes/H'Depot and install it in the cord, near the base. It's easy to do and is much more convient than having to pull the plug to start/stop the thing.
It can be irratating to seperate cases and media, a sifter makes it easy. A cheap sifter can be "assembled" for cheap. Get a 5 gal. plastic paint bucket, with lid, from a home supply, costs a couple bucks. Go to a Dollar General, et al, store and buy an expanded mesh office trash can, also a couple bucks. Set the basket in the bucket, pour in the tumbler contents. Tilt it to one side and rotate the basket, a few back and forth twists will do the job nicely! Store the bucket with the lid on to keep it clean.