Kalkwasser Instructions

Kalkwasser, also known as Kalk and Limewater, is arguably the easiest and cheapest Calcium and Alkalinity Solution for low to medium demand tanks and our recommended solution for people new to the hobby. Kalk also has the benefit of raising pH. It is frequently used with auto top off systems or slowly dripped into the tank.

Step One: Raising Calcium and Alkalinity to their proper levels.

Before beginning Kalkwasser dosing it is necessary to test and raise calcium and alkalinity levels to their proper points.  Kalkwasser should not be used for this step because in large doses it will significantly raise pH. Instead use Calcium Chloride and Sodium Bicarbonate (Baking Soda) to raise your Calcium and Alkalinity. See below for directions on how to mix and dose for this step.

Mixing the Calcium and Alkalinity for Step One

Calcium

• 1. Fill a gallon jug ¾ to 4/5^th with RO/DI water. This will make shaking and dissolving the solution much easier.
• 2. Measure out 1 cup of "High Purity Anhydrous Calcium Chloride." Add 1/2 of this to the jug, cap and shake vigorously.
• 3. Repeat "Step 2" with the remainder of the Calcium.
• 4. Fill the remainder of the jug with water, cap and label "Calcium."

Alkalinity

• 1. Fill a gallon jug ¾ to 4/5^th with RO/DI water. This will make shaking and dissolving the solution much easier.
• 2. Measure out 1 and 1/8^th cups of "Sodium Bicarbonate." Add half of this to the jug, cap and shake vigorously.
• 3. Repeat "Step 2" with the remainder of the Sodium Bicarbonate.
• 4. Fill the remainder of the jug with water, cap and label "Alkalinity."

Dosing Calcium and Alkalinity for Step One

• 1. Test your Calcium and Alkalinity levels.
• 2. Use our Reef Calculator to determine how much of each part to add. Select "Recipe 2 Calcium" and "Recipe 2 Alkalinity" from the drop down menus.
• 3. *Spread the recommended adjusting doses out over a few days to avoid shocking the system. Be sure to dose each solution separately and slowly to high flow areas of the tank. This is especially important when dosing the Alkalinity portion as temporary decreases in pH will occur.*

Step Two: Maintaining the New Levels

Dosing Kalkwasser with an Auto Top Off

The typical Auto Top Off uses a container to hold the Kalkwasser and a float switch/valve that activates a pump that pumps it into the tank as water evaporates. All you need to do is mix Kalkwasser with fresh water in the container and set up the Auto Top Off system. Start with the recommended amounts below, test every few weeks and adjust as necessary until Calcium and Alkalinity levels are maintained.

Determine how much Kalkwasser to mix with the Auto Top Off water by using the table below. "Per gallon" refers to the number of gallons in your Auto Top Off system, not the total system tank volume.

The maximum amount of Kalkwasser that can dissolve in fresh water is 2 teaspoons per gallon of water. If you find that you are using the maximum of two teaspoons per gallon of fresh water and it isn't keeping up with the tanks demands consider switching to the popular Two Part Solution.

You may also buy or build an inexpensive Dripping Jug rather than use an auto top off. This is a good way to get comfortable with Kalkwasser but rarely considered to be a long term solution since it tends to become clogged a lot and the drip rate is very inconsistent. They also require daily additions of Kalk and fresh water.  

Step Three: Raising Magnesium (optional)

Maintaining magnesium is important as it plays an essential role in maintaining stable levels of calcium and alkalinity. This step as optional because in low consumption tanks water changes might be enough to maintain magnesium levels. We recommend using magnesium chloride to adjust the levels. Magnesium is frequently neglected so it often requires a substantial amount for the first adjustment. After making initial adjustments using http://www.2partcalculator.com/ you will find that magnesium levels drop rather slowly and in most tanks an adjustment every few months will suffice.