A method and system of controlling operation of a diffusion appliance to treat the atmosphere within an enclosed space. The appliance may be programmed to operate according to a control scheme specifying a flow rate of liquid to a diffusion means and a periodic operation of the diffusion means. Control schemes may be associated with different volumes of spaces to be treated by the appliance. Anti-fatigue schemes may provide variation of the flow rate or periodic operation of the appliance. Initiation controls schemes may be used to start treatment of the space before the appliance is programmed to operate according to one of the control schemes.