A process for preparing a disinfectant for use in swimming pools and the like. The fin consists of a metal strip having a width divided into at least two heat-exchange regions by at least one series of longitudinal oblong holes spaced apart from one another. In response to the initial touch input, the interactive element can displayed in the user interface. The shroud shield may be formed as separate plates located on each inner shroud wall and may include springs for engaging a metal panel. In addition to acting as a gas control additive, methylhydroxyethyl cellulose controls fluid loss, minimizes free fluid and stabilizes foam during cementing of the well.