Starting in the fast, streamy neck of a pool, the strong flowing water found here makes casting and negotiating the flies downstream hectic to say the least. So it's best to fish a shorter, more controlled, line.
The best way to achieve this is to use the Czech nymphing method. This involves pitching the weighted nymphs, leader and a short section of fly line upstream. Fished close together, the team of heavy flies sink quickly. Here's how to do it. Hold the fly line clear of the water with the rod tip and guide your team of flies downstream. Remember to swing the rod at a slower speed than that of the surface current.
Down on the stream bed, flow rates are reduced because of friction between water and substrate. Takes are generally signalled by the fly line section halting, or stabbing forward, in a very positive manner.
This technique allows the angler to cover a lot of water quickly and accurately. With a little practice, a taking fish can be distinguished from the flies merely bouncing bottom.
Fish the main body of a pool with heavy nymphs and you will soon snag the bottom. A more subtle approach using lighter flies and finer tippets is now called for. I prefer to fish two nymphs close together, with a third acting as a sweeper, some distance up the leader.
Away from the turbulent water, trout are more easily spooked. Fishing slightly-longer lines not only avoids scaring fish; it helps work the flies in the medium-paced water.
High-sticking is ideally suited to such circumstances. The rod is held high with outstretched arm to keep as much fly line as possible off the water. Thus, there is virtually no influence on the line from swirling water.
A cast of two to three rod lengths is made up and across the flow. If the current is quite strong then throw an upstream mend.
Now lift the rod high and track it downstream, level with the fly line. Watch the bow of fly line from rod tip to water. This lifts when a fish takes your fly.
Deeper, faster water can be fished with such a rig by simply casting more directly upstream. This way, there is less influence from the current, allowing the flies to plunge deep. This method will allow you to explore deeper water, which is not accessible by wading.