Nymphing with an indicator requires a rod with a little more backbone, so something between a 5-6 weight rod is the best tool for the job. I run 3x fluorocarbon to my top (point) fly and 4x fluorocarbon to my bottom. That way, if I snag the bottom fly, I can break it off without losing my whole rig.
I often call my leaders a “Frankenstein” leader because of all the knots I end up tying in them. Since we are using an indicator and two often heavily weighted flies the rig turns over with ease and a nice clean tapered leader is unnecessary.
When we are nymphing, we have typically three moving parts: the indicator and two flies (typically weighted).
In order to turn this rig over so it doesn’t land in a puddle of line in front of us, we want a fast action rod. You are going to have a hard time with a 4-weight or slow action rod while nymphing as it doesn’t have the muscle to cast a heavy rig.
The Scientific (SA) Anadro line is top shelf quality, nothing beats it. It is 1.5 times overweighted and has a slow taper in order to transfer energy all the way to the indicator when mending. It is a top-shelf nymphing line. Anadro stands for anadromous which is what this line was made for, anadromous fish. When the line began gaining popularity, SA made it in lighter grain weights for trout and it is a killer nymphing line.
I use this line when I know all I’m going to be using it for is indicator fishing. This line will also double as a streamer line if needed because of its grain weight. I would recommend sticking with the true rod weight instead of bumping up a weight as stated above it is already 1.5 times heavy. For a Rio line use the InTouch trout/steelhead indicator line.