Re: Discerning a strike from the bottom
It sounds to me that you might have a problem with your technique or you are casting too far up stream. If you cast too far up stream with a weighted fly or with split shot, fast water will wash the fly to the bottom. You may need to adjust the amount of weight your are using or adjust your indicator closer to the fly. With fast shallow water you need the indicator much closer to the fly. That is instead of 7 or 8 feet from the fly it may need to be 3 to 5 feet from the fly.
Try casting 45 degrees up stream instead of 30 degrees. You may also be getting too much slack in your line. When you mend line you don't want to have huge big S curves on the water. It makes it much harder to strike or control the fly.
When I am fishing nymphs or wet flies I seldom strike and get the bottom. I may get hung up but not due to a strike. If you are striking and getting the bottom frequently then you need to adjust something in your technique. Use less weight, cast more across the stream or river, adjust the indicator, adjust your drift. Subsurface fishing is a learned endeavor and you need to analyze what is happening every time you hang the bottom. To me hanging up on the bottom is different that striking and getting the bottom. You may just need to get more experience and this problem will go away.