I fish this set up all the time. Usually some type of hopper with another dry or bead head nymph below. Improved clinch knot tied to the bottom of the hopper hook and the same knot for the eyelets on both hooks. This rig can be a real pain if it's the least bit windy, or if you get sloppy with a cast. The dropper can be tied whatever length you wish, but generally the longer it is the more issues you will have. When it gets tangled it will not be easy to get sorted out. On too many occasions I have resorted to using the clippers, cutting the hopper from the tippet and starting again. That said, I have caught many fish on the dropper! Hope that helps and good luck!
