These filters are custom engineered and built to order based on the results of a comprehensive water analysis. Crusader pH Neutralizing filters are used where low pH water is a problem. Naturally occurring acidic water and potable drinking water, such as that produced by Reverse Osmosis, can be effectively neutralized by using special neutralizing media. The media will require periodic replacement as it is consumed in the neutralization process. Calcium and magnesium carbonates are introduced into the ionic makeup of the water during neutralization, which may necessitate the installation of a water softener to reduce the hardness of the water.