These inserts contain coral calcium and have added magnesium. They dissolve slowly and typically last from 4-12 months (depending on water condition and usage).Thsee calcium inserts fit the Jupiter Ionizers - Melody, Aquarius, Orion, Athena, Delphi, and Neptune as well as some Ion Farms and Alka Blue models. Will also fit the Amwater AMWS903 Ionizer.
