Use indicator. Live midges (midge pupa) float and wriggle around in the water column as they slowly rise up from the stream/river/lake bed and make their way to the surface to hatch and fly away, so the indicator is not only used to see a strike, but also to set the depth for the fly. Since live midges passively drift with the current, the goal is to mimic this action by setting the fly at a depth where it will passively drift into the face of a fish (ideally), which are normally hovering just above the stream bed, but can be anywhere in the water column. If a 'hatch' is taking place, the fish will be near the surface focusing on the food source, so setting the fly to drift near the bottom isn't going to be as effective as setting it up higher in the water column where the fish are. If the fly is set to drift too low, it will just get caught up on everything and won't drift naturally. HTH