Aqua-Rex will get rid of Calcium scale but will have little or no effect on Silica scale. Silica scale is only an issue in a few areas of the country where Silica rich water is drawn from wells. Silica scale won’t react to acids such as vinegar or Muriatic and can only be removed by using abrasives. Sometimes you will find all the scale disappears and then a thin layer recurs, especially around the grout line. This is most likely to be Silica, and Aqua-Rex nor any device on the market is able to remove it electronically.