How much does the Millbank (or other canvas seep bag) weigh?

1. To filter out large chunks of sediment, the material in pantyhose works as a pre-filter. For best results, use multiple layers. You get good flow rate through the material.

Pantyhose also works well as a mesh bag for keeping food cool in stream or lake. Can be made into bug-netting. Lots of uses. I recall reading somewhere that they also work well as bottom liners to keep your hiking pants from binding on your legs, but I haven't tried that trick myself yet. Their mesh construction should let them work like a thinner version of mesh underwear (ala Wiggy's mesh nylon tops & bottoms).

2. To filter finer chunks of sediment, why not carry a few paper coffee-maker filters? They cost next to nothing per filter, are lightweight, and can fold up small enough to fit in the corner of a pocket. Plus, being made of paper, they are multi-functional.