CRCST Practice Exam 2026 – Complete Study Resource

Descalers are typically used to remove hard water deposits or scale buildup. These can include substances such as calcium carbonate, calcium sulfate, and magnesium hydroxide. An aqueous solution, or just water, would not be effective in removing these substances. Chlorine residue can be removed with a different type of cleaner, and grease buildup would require a degreaser. Therefore, option C, the chalky white substance, is the only correct answer that describes what is specifically removed with Descalers.