That leads to my next question, haha. How would I separate out cobble stone and other items after they get pulled out of the filter and go into a void pipe?You could prime each barrel with one item of the type for that barrel. Thats the normal way to set up barrel walls. Any barrels that are not primed will end up with something random in them, so you will probably end up with loads and loads of cobblestone and dirt barrels if you pipe a quarry into it.
I put in some iron bars to see if items would round the corner, and they did, but they each filled their own barrel, and didn't go in to one barrel. Why's this?