Purchased 15 pounds from Midsouth reloading for $9 . had to order other stuff so only added a dollar to the freight bill.
Been using my current media for 20 k hulls or so . getting kinda dark or black. but stil works but I generally let my home made seven gal bucket tumbler run for 12 hours. or bit more
guess changing is just a matter of wild guess and want cleaner looking media.