Calcite filters are commonly used in low pH or acidic water occurs. Calcite can balance your water to a perfect pH level of 7. As a division of ResinTech, Aries FilterWorks applies the technology and knowledge of ion exchange and specialty adsorbents in each cartridge. Our strict quality control over all aspects of cartridge production allows complete traceability of every filter. Features: Balancing and correcting pH problems in acidic water Manufactured using an FDA-compliant materials. Cost effective cartridge compared to other brands Initial flushing instructions: Rinse with no less than 10 bed volumes of water before use Dimensions: 20" x 2.5" Fits 20" Big Blue filter housing Temperature Rating: 40F to 100F (4.4C to 37.8C) Part Number AF-20-3231 Manufactured in the USA