The US Water Calcite Neutralizer System is designed to raise the pH of the water supply

Calcite is a naturally occurring calcium carbonate media. One of the advantages of Calcite is its self-limiting property. When properly applied, it corrects pH only enough to reach a non-corrosive equilibrium. It does not over-correct under normal conditions. Upon contact with calcite, acidic waters slowly dissolve the calcium carbonate to raise the pH which reduces potential leaching of copper, lead and other metals found in typical plumbing systems. Periodic back-washing will prevent packing, re-classify the bed and maintain high service rates. Depending on pH, water chemistry and service flow, the Calcite bed will have to be periodically replenished as the calcite is depleted. As the Calcite's calcium carbonate neutralizes the water, it will increase hardness and a softener may become necessary after the neutralizing filter.

Upflow calcite is perfect for whole-house reverse osmosis to raise the TDS of the water for use with copper plumbing

Not sure what size filter you need? Remember, it's always better to go a little too big than too small.