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Reef Kalkwasser
Product Description

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).

Many who use kalkwasser are quite successful with their marine systems and find it to be an effective way of maintaining calcium. However, it can be a difficult technique for the beginner to master. The carbonate alkalinity must be monitored and adjusted to ensure that it does not become depleted through chalk (calcium carbonate) precipitation. The magnesium concentration must also be monitored and maintained since precipitation of magnesium hydroxide (arising from excess hydroxyl ions) can lead to a change in the balance of the various buffer systems present which can result in drastic pH shifts. Additionally, magnesium is an essential component of seawater that is required by all corals. There will be an increase in the build up of chalk on substrate and plumbing surfaces which will require more frequent cleanings in order to maintain the proper functioning of the aquarium. If due care and diligence is paid to all of these factors, there is no reason one cannot maintain a successful reef system while using kalkwasser. While 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.

Sizes: 250 g, 500 g, 1 kg, 2 kg, 12 kg


Never add this product directly to the tank. Add 3 g (1 teaspoon) to 4 L (1 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 gallon*). Drip this solution into tank. Monitor pH and carbonate alkalinity. Adjust rate of addition to maintain a stable pH (8.3–8.4). HINTS: Adding 4 L (1 gallon*) of a saturated kalkwasser solution to 150 L (40 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.

Avoid contact or breathing dust. Do not eat or get in eyes. In case of contact, flush area with water for 5–10 minutes. In case of eye contact, wash eyes with water immediately (5–10 minutes) and seek medical attention.