Eradicator Fungus Gnat Drench is highly effective against the larva stage of the gnat where the damage is done. When infestation has occurred use weekly until no live gnats are present. For good coverage water plants with normal feed solution until run-off occurs. Wait an hour and drench with the prepared gnat solution evenly across the entire surface of the pot using a milk bottle with holes poked in the lid like a showerhead. Repeat if necessary.