Growstone Gnat Nix 1.5 cu ft (60/PLT) Gnat Nix! is the only scientifically proven, environmentally friendly fungus gnat control product on the market Trials at Kansas University have shown that used as a top dressing, Gnat Nix! is an effective physical barrier against fungus gnats Gnat Nix! controls gnats at different points of their lifecycle, preventing adult emergence from hatching larvae and deterring females from laying eggs in the growing media