Had a few people asking me on this thread my leader line/main line combo.
Mainline is PLine CPX, or something along those lines. To be honest, I hate it, made a switch today to a different type of 20 pound PLine that is thinner, so we'll see how that goes on the next outing.
My leader is Seaguar blue label, or red label, to be honest they aren't much different, but the red label is way cheaper. I just double checked the label on the line and it says the 15 pnd is actually the same diameter of 12 pnd test, but it's still thin and it seems even in the slowest, clearest water, it hasn't made a difference on spooky fish. I'm convinced I could run 20 pound flourocarbon and not have it cost me fish at this point. The only time I have ever seen line diameter in flouro make a difference is with spooky low water lock-jawed coho and rainbows. Lowest I go is 8 pound flouro and that will get any fish to bite.
As for the knots I use... I just use a basic improved clinch knot for attaching to the swivel, I haven't had any problems with breakage at all, even when really putting the breaks on fish. Attaching to hook I use a basic bait loop knot. Just make sure you wet your knots before pulling, and pull slow until the knot tightens up, then pull hard. You shouldn't have problems with flourocarbon breaking....
PS Some one above said the Berkley transition flourocarbon is good (the brown/gold stuff). It's trash... I broke off 15 fish in a row on the hook set (thank goodness I tried this on coho first). I wouldn't recommend it to anyone, threw 300 yards of it into the trash. Maybe I had a bad batch, but I'd never try it again....