When bobber fishing for catfish, how far from the bottom are you aiming for? Do you just randomly pick a depth for a slip bobber and go with it? Is there a method, while fishing from the bank, to establish depth and maybe move the bobber up about a foot to keep the bait barely floating? I have a grassy bottom at the local lake and I see quite a few using bobber when fishing and they do pretty well, just wondering how folks work em when not going from a boat.