In Clark’s process to remove temporary hardness, which is added?

Clark's method is a water softening method to soften water containing bicarbonates of calcium or magnesium. In this method, calcium hydroxide (slaked lime) is used to convert the the soluble bicarbonates into insoluble carbonates, which is then filtered off to obtain soft water.

$Ca{\left(HC{O}_3\right)}_2+Ca{\left(OH\right)}_2\to 2CaC{O}_3+2H_{2}O$