Block salt is sometimes used for home softeners, but it is not suitable for larger installations because:

• A. It is too expensive
• B. It does not clean well
• C. Its small surface area does not allow it to dissolve fast enough
• D. It has a low purity level

Answer: (C)

Block salt is utilized in some home water softeners due to its convenience and ease of handling. However, it is not suitable for larger installations primarily because its small surface area limits the speed at which it can dissolve in water. In a larger system, a more significant amount of salt is needed to effectively soften water, and the slower dissolution rate of block salt can result in insufficient regeneration of the resin beds. This slow rate can lead to potential problems in maintaining appropriate water quality and efficiency in larger softening systems.

Alternatives such as granular salts or salt pellets have a larger surface area, which allows them to dissolve much more quickly and efficiently, making them far more suitable for larger scale applications where rapid regeneration is essential to maintaining performance.