I only get about $120.00 in clad a year. I have a Lortone model 3A, which is the smallest capacity tumbler they make. The barrel holds about 16 - 32 fl oz. I usually have to tumble 3 - 4 batches of pennies, and 2 - 3 batches of quarters/nickels/dimes, once a year. If I was finding more, I'd do more batches. There were times I was tumbling once a month, usually a batch a pennies, and a batch of quarters/nickels/dimes.
Some of the beach hunters get so much clad, they need a bigger tumbler, or one that can handle 2 - 3 barrels at a time.
I use a handful of aquarium gravel, fill the barrel with enough coins to come up to 2/3 full, just cover the coins with hot water, add a squirt of dishsoap, seal it, and away we go. I usually tumble a batch for 4 hours, although, on some really nasty stained clad, I've been known to go longer. Also, when I dump the clad and strain it to dry, I separate the ones that are still stained, and run them through again.
HH from Allen in MI