Calcium Supplement Mix for Reef Tanks

Our pure source of Calcium Hydroxide makes the ideal solution for replenishing calcium and maintaining alkalinity, for corals, clams, and calcareous algae that build skeletons of calcium carbonate. It also helps maintain pH, precipitates phosphates and enhances protein skimming.

Two Sizes Available:

1.1 Pounds
4.4 Pounds

Using Kalkwasser (Calcium Hydroxide)

Fill a 1-gallon container 4/5 full of RO/DI or distilled water and add 1 cup and 2 tablespoons (302 grams) of BRS Pharma Sodium Bicarbonate. Secure the cap on the container and shake it for about 10 seconds to help start the dissolving process. Remove the cap and fill the container the rest of the way with RO/DI or distilled water. Give the container a few more shakes and then let it sit until all the salts have fully dissolved before use.

We suggest adjusting your Calcium, Alkalinity, and Magnesium parameters to normal levels before using Kalkwasser.

How to Use Kalkwasser with an ATO System

Step 1: Test and adjust your aquariums calcium, alkalinity, and magnesium levels.

Step 2: Start by establishing the proper amount of kalkwasser to mix into your aquariums top off water reservoir.

Low Demand - 1/2 teaspoon per gallon of top off water
Medium Demand - 1 teaspoon per gallon of top off water
High Demand - 1 1/2 teaspoons per gallon of top off water

Step 3: With RODI water fill your top off reservoir & mix in the proper amount of kalkwasser then allow the solution to settle for 30 minutes before using.
DO NOT OVERMIX: Excess mixing and air contact will decrease the potency of kalkwasser.

Step 4: Place your ATO systems pump or intake line is place 1/2" to 1" above the base of your reservoir, ensuring only the clear slurry is being dosed.

Step 5: Activate your ATO and monitor the pH of your aquarium as the kalkwasser solution is being dosed, not exceeding increases of 0.20 pH. Your ATO should be pumping water into a high flow area of your sump or display tank to help prevent precipitation. Adding kalkwasser too fast may result in precipitation rendering it ineffective.

Step 6: Monitor your aquariums calcium and alkalinity daily, adjusting the strength of the kalkwasser solution in your top off reservoir as necessary.

Note: We highly suggest using a pH controller to prevent against pH spikes and overdosing.

Refilling The Reservoir

Simply refill your container with fresh RODI water and add the proper amount of kalkwasser per gallon of new RODI water and mix. It is recommended to clean your ATO reservoir regularly, though you do not have to every time you replenish your ATO container.

Maximum Dosage - 1 1/2 teaspoons per gallon of top off water

One of the limitations of kalkwasser is its 1 1/2 tsp. per gallon saturation point. Anything more than that will simply fall to the bottom of your reservoir and become essentially useless. If your aquarium is requiring more calcium and alkalinity added than what kalkwasser can keep up with there are a few solutions;

Start 2-part dosing
Increase your aquariums evaporation rate with fans
Vinegar method (experts only)

How Does Kalkwasser Work?

Kalkwasser or Calcium Hydroxide Ca(OH)2 when mixed with fresh RODI water contains a perfect balance of alkalinity and calcium ions that can be added to your aquarium to help supplement what your corals consume when they grow. It is pretty easy to see where the calcium is derived from but the alkalinity can be a little more difficult to see, and when Kalkwasser is added to your saltwater tank a simple reaction takes place converting the hydroxide into available bicarbonate ions. Essentially the CO2 in your water and atmosphere will react with the hydroxide ions creating bicarbonate ions and increasing your tank's pH, due to less available carbon dioxide.

Ca(OH)2 = Kalkwasser

OH- + CO2 = HCO3 = Bicarbonate

OH- + HCO3 = CO3-- + H20 = Carbonate + Pure Water

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