Abstract: A simple and inexpensive adaptor is provided for a commonly used household vaporizer to reduce and control its rate of vaporization. A thin insulating sleeve or tube is placed around one or more of the electrodes to lengthen the path of the current so as to reduce its strength, and thus the rate of vaporization, whenever the hardness of the water supply is too high. By selecting the proper length of tube, or a tube with the proper size of perforations, the current strength is easily adapted by the user to the water hardness to produce the desired evaporation rate."Also, for clarity's sake, in the disclosure and claims, the term 'to adjust the adapter sleeve' means a one-time or occasional change of its length while the vaporizer is not operating, as clearly distinct from any continual variation during the operation of the device.