Ive heard that the knots can slip but I have not had trouble! I use a trilene knot. Make sure you moisten it as you tighten it.Ive caught good sized fish without any not slippage.

i do a lot of nymph fishing and the flouro works the best. mono leaders with flouro tippets. its important to use the right knots, a double surgeons knot when tying mono to flouro works better for me than a blood knot, or use a small swivel for trolling. for trolling i use cortland camo with a tippet of 4 pound flouro about 6 feet long. sometimes when the water is muddy as some of the northern lakes get muddy at ice out i use just the camo line. lately ive been using a loop knot to attach lures with split rings, i havent had one fail this year and ive been changing lures with split ring pliers instead of retying every time. occasionally i do change the loop in fear that the old knott may weaken, but may chnage the lure several times before retying. one of the things i find with the flouro is that it gets weak with age. every once in a while test it with a scale.

Fluor is definitely the best leader. If you use an attractor ahead of the lure, then you can go mono to the attractor and fluor to the lure. 4# or 6# may be fine for tying right to a lure but you should step up to 8# or even 10# fluor when using an attractor or flasher / dodger. If you use a dodger, go with the 10#. Lighter leaders can get all tangled and twisted, even with swivels, from the action of tha attractors. I got these tips from Alan at AJs bait and tackle.