I run warm tap water to start -- we're in NJ with city water so whatever chemicals they add
You have to rinse a few times -- the dirty water looks like black coffee on the initial dump after a run --
also can't let the cleaned brass sit undisturbed in a dirty drum -- if you can't rinse it right away thats fine just run it for 30 minutes before you dump it -- just to shake the crap up so it pours out
Then rinse, rinse, rinse