Final answer:
When cleaning a foot spa, you should fill the basin with water and chelating detergent to effectively remove inorganic deposits.
Step-by-step explanation:
When cleaning a foot spa at the end of the day, you should fill the basin with water and chelating detergent. Chelating detergents are effective for removing inorganic deposits like scaling. They contain chelating agents which help bind and remove the mineral deposits from the surface.