Calcite is a naturally occurring calcium carbonate media. Calcite neutralizes low acidic pH conditions and re-mineralizes reverse osmosis water. These cartridges will make water less aggressive and many prefer the pleasant taste added to drinking water. The media is dissolved during filtration, thus the cartridge should be replaced prior to complete depletion. As the Calcite's calcium carbonate neutralizes the water, it will increase hardness and a softener may become necessary after the neutralizing filter. Features: Naturally occurring material Inexpensive Slow reacting for controlled pH correction Self-limiting NSF standard 60 certified Calcite TM media. Specifications: Micron Rating: 10 Micron nominal Dimensions: 20" x 4.5" Weight: 15 lbs 10 oz Operation Temperature: 40 F to 100 F Flow Rate: 4 GPM Filter Media: Calcium Carbonate Filter Life: 24,000 Gallons