What is a calcium hardness increaser?

A calcium hardness increaser is a common pool and spa chemical that adds calcium into the water system. It is intended to harden the water and prevent damage to plumbing and tile fixtures.

When a calcium hardness increaser is added, the hardness of the water is increased, which can benefit water that is too soft, helping raise it to a balanced condition. Water that is too soft can corrode pool plumbing and heating, as well as cause damage or staining to tile. Water testing strips can verify the content of calcium, notifying the user of which chemical needs to be added to maintain balance.