As with all fishing there is never a definitive answer. I use the formula 1' beyond the visibility of the water some of the time. With high visibility water, long leaders do hook more fish think about sound waves from the ticking of your lead if it's clear water I think the fish can get a little jumpy then again.... As for color of your bobber/corkie I think contrast of the lure is more of a contributing factor If I remeber right aren't fish colorblind so all they see is different shades but we all know things are dead you change colors and wham forest green and black seem to be working for me this year jmy .04 good luck on the Green