Picture a beautiful evening, my buddy and I camped on the shore of Lake Superior (Isle Royale), filtering water after a perfect day's hike. As we finish, I notice him grasp the hose on his filter and begin to windmill it, really fast, so centrifugal force will spin the water out of the hose.

Monkey see, monkey do - and I'm watching the pre-filter make a long, graceful arc about 30 feet out into Lake Superior, never to be seen again.

Duct-taping a small rock to the hose served the same weighting purpose as the pre-filter (though much less aesthetically), but I had to disassemble and clean the filter twice as a result.

At least my buddy enjoyed it - a lot! (He also stopped using that technique.)