Mosquito bits works like a charm for me. I measured and soaked them according to directions, strain them out, then used the water to soak my soil. I waited until after a pretty significant dryback before watering thoroughly. No more fungus gnats. Now a light top dress after transplant has become standard practice for me.

The BT will help knock them back but not get rid of them. Got to break their life cycle to do that. Hydrogen peroxide is quicker and more effective killer of eggs, larvae and pupa. But that’s not even enough to eliminate them if the surface of the media stays wet.

If you use them at the first sign of a fungus gnat problem you should be able to get rid of them quickly with the dunks in my experience with them!