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Seachem Kalkwasser

Seachem Kalkwasser

Regular price $24.00 SGD
Regular price Sale price $24.00 SGD
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Seachem Reef Kalkwasser contains pure calcium hydroxide and is used for increasing the calcium in top-off water. This ensures the corals in reef aquarium have a reliable supply of calcium in the water which is essential for them to thrive and grow.


Seachem Reef Kalkwasser is a pure calcium hydroxide with unsurpassed purity and solubility characteristics. Calcium hydroxide is used to prepare limewater (kalkwasser) solutions that will maintain calcium concentrations at natural seawater levels. Kalkwasser solutions maintain calcium directly and carbonate alkalinity indirectly. However, its capacity to perform these functions is dependent on evaporation rate and CO2 concentration. If these two factors are insufficient you can provide additional calcium with Reef Advantage Calcium, Reef Complete, or Reef Calcium, and carbonate alkalinity with Reef Builder or Reef Carbonate (do not mix these directly with a kalkwasser solution).

While Seachem Reef Kalkwasser is a high purity and economical limewater mix, the beginner, or someone with not as much time to devote to their system, may prefer to use other less involved methods for maintaining proper ionic concentration levels.


Ingredients: calcium hydroxide

Amounts per 1 g:

  • Calcium (Ca) (min) 535 mg
  • Calcium (Ca) (max) 540 mg

When mixed as directed (saturated kalkwasser solution):

  • Calcium (Ca) (min) 0.9 mg
  • Calcium (Ca) (max) 0.9 mg


Never add this product directly to the tank. Add 3 g (1 teaspoon) to 4 L (1 US gallon) of water and mix to dissolve. If using pure water, a fully saturated solution is prepared by adding 6 g (2 teaspoons) to 4 L (1 US gallon). Drip this solution into tank.

Monitor pH and carbonate alkalinity. Adjust rate of addition to maintain a stable pH (8.38.4). Notes: Adding 4L (1 US gallon) of a saturated kalkwasser solution to 150 L (40 US gallons) will raise calcium by 24 mg/L.

Always use the clear supernatant (top solution) only and do not allow undissolved material to enter the aquarium. Keep this container tightly closed when not in use and minimize solution/air contact to avoid calcium carbonate formation/precipitation.

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