If the water to be treated already has a high sodium concentration, the cation exchanger will no longer be able to absorb any further sodium ions. On the contrary, it will even release additional sodium ions, as it will exchange calcium ions back into sodium ions, so to speak. This phenomenon is known as the COUNTERION EFFECT. When a plant is at a standstill and as a result there is a rerelease of ions from the partially charged exchanger, this is also referred to as a COUNTERION EFFECT in a wider sense. However, this variant of the COUNTERION EFFECT can be prevented by a circulation system that keeps the water moving.