Right from the pen of Lefty Kreh, one of the greatest fly fisherman to ever walk the face of this Earth. Here is a quote from his article Nymphing Tactics for Big Trout: "Since the fly needs to be close to the bottom almost all imitations carry some weight. When fishing floating lines some weight in the fly is almost always necessary. But remember that too much weight makes the fly devoid of life as it moves across the bottom. The trick is to combine some weight with the different sinking tips so the fly gets into the feeding zone but drifts naturally. An indicator helps the fly fishermen know when to strike. Indicator size varies with the fly. The indicator must be buoyant enough to keep the fly from dredging the bottom. With lighter flies the indicator is small, but when using larger and heavily weighted flies indicators, are usually of buoyant yarn. It can be huge, as large as a golf ball!" I had the privilege of fishing with him during my guiding days, and he is an amazing individual and a world class fly fisherman.