If your not having implosion problems I would say you either have leaks in the system or the system suction is low enough for you to not have an issue. We have a 3HP cyclone that folded up a fiber drum that got dented on the edge of the dumpster.

If you have any leaks around the lip of the drum/below the cyclone, your filter will be constantly plugged with fines. But it looks like a great setup and 2HP should be manageable.