KENT MARINE KALKWASSER MIX provides supplemental calcium to reef inhabitants while promoting growth of purple, pink, and green calcareous algae. This application is the original European method of adding calcium to a reef aquarium. Not for the beginner aquarist, using Kalkwasser requires more work, but is proven to provide sustainable long-term results. See packaging for special mixing instructions and should be dosed slowly via a drip method.