I've read some of the posts and they've been helpful. Is the solid white plastic pipe better to use than the black corrugated pipe? If so, what size should the pipe be and is there a "sock" that should go over the white plastic pipe like the one that goes over the black corrugated pipe? Someone told me that the pipe that runs around the perimeter of the basement doesn't have to run downhill to the sump pit. But this doesn't sound right to me. Does it have to run downhill? If so, what kind of fall does it need to have? Thanks for any help.