Groupe H2O

Neutralizing filters

What is a neutralizing filter?

A neutralizing filter is a device that increases the pH of the water with the help of a filter medium, i.e. a filtering material, called neutralizing sand. It can thus reduce the acidity of the water.

When water is very acidic, it is said to be aggressive. It then tends to attack copper and other metals in its environment. To avoid this problem, a neutralizing sand is used to restore the water balance.

The neutralizing sands on the market are Calcite and Corosex. These are materials that mimic the natural filtration that would occur if the water passed through rocks. As rocks would do, these sands add hardness and alkalinity to the water to reduce its aggressiveness. By using these products, we imitate nature.

Here are the main characteristics of the two main neutralizing filters we use at Groupe H2O:


  • Increases water hardness.
  • Contains calcium carbonate.
  • Dissolves slowly.
  • Corrects the pH slightly.
  • Is easy to dose.

The Corosex:

  • Increases the hardness and alkalinity of the water.
  • Contains an oxide of magnesium.
  • Dissolves quickly.
  • Corrects pH quickly.
  • Is less easy to dose.

The use of Corosex and Calcite gives good results. However, the results are difficult to predict. Also, we must check the performance of the neutralizing filter once a year.

Installation : $

Maintenance : $

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