Kalkwasser

Definition

Kalkwasser (German for "lime water") is a saturated calcium hydroxide solution used to maintain calcium + alkalinity in reef tanks via slow drip-dosing. Each 1 mL of saturated kalk contributes both Ca and bicarbonate to the system.

Practical use in aquariums

Mix 1-2 teaspoons of Mrs. Wages Pickling Lime per gallon of RODI water; let settle, drip the clear top water at a rate matching evaporation. Auto-top-off (ATO) systems often dose kalk in place of plain RODI for two-in-one calcium + alk maintenance plus stable salinity.

How Kalkwasser fits the bigger picture

Understanding Kalkwasser matters because it's connected to broader husbandry decisions: water chemistry is the foundation of every other aquarium parameter - chemistry mistakes show up months later as livestock loss.

Browse the Fast Aquatics care library for full husbandry tutorials covering Kalkwasser in context.