Kalkwasser Calculator
Formula: Kalk mix ≈ up to ~2 tsp of kalk powder per gallon of top-off water (saturated limewater)
Enter your aquarium details to calculate your Kalkwasser dosing needs.
About the kalkwasser calculator
Kalkwasser (calcium hydroxide) is a proven method for maintaining calcium, alkalinity, and pH in reef aquariums. When mixed into freshwater and dosed gradually, it replaces calcium and carbonate ions consumed by corals, clams, and coralline algae, helping support vibrant growth and stable water chemistry.
Our calculator helps you determine the precise amount of Kalkwasser solution and powder needed for your system, based on real-world parameters like evaporation rate and top-off percentage.
Why Use Kalkwasser?
Kalkwasser offers multiple benefits:
- Replenishes calcium and alkalinity in one simple dose
- Helps maintain stable pH by consuming excess COâ‚‚
- Promotes healthy skeletal growth in calcifying organisms
- Provides a cost-effective alternative to two-part dosing or calcium reactors
However, it must be used carefully, as adding too much too quickly can cause sharp pH spikes or precipitation events.
Start Slow: Recommended Usage
Note: The calculated values are suggested starting points and should be applied gradually.
Start by mixing a maximum saturation of about 2 tsp per gallon of freshwater. Dose half the calculated daily volume at first, monitoring calcium, alkalinity, and pH over several days.
Avoid pouring kalkwasser directly into the display tank. Instead, add it slowly using an ATO system, dosing pump, or drip system to minimize sudden chemical changes.
How This Calculator Works
This calculator estimates your daily and long-term kalkwasser dosing needs by using three main inputs:
- Tank volume
- Daily evaporation rate
- Make Up %
Based on these, it provides:
- Daily kalkwasser volume in gallons and milliliters
- Amount of kalk powder in cups needed for 14-day and 30-day supply periods
- Estimated daily alkalinity increase in dKH to help track system stability
Best Practices for Dosing Kalkwasser
- Mix only clear solution. Allow sediment to settle before dosing
- Store mixed solution in an airtight container to limit COâ‚‚ exposure
- Add slowly over time via ATO or dosing system to avoid pH spikes
- Monitor calcium, alkalinity, and pH regularly during and after dosing
- Do not combine with other calcium or alkalinity supplements unless calculated carefully
Frequently Asked Questions
How much kalkwasser can I dose?
Only replace evaporated water with saturated limewater, and never dose more kalk than your daily evaporation. Kalk is potent, so dose it slowly through an ATO, ideally at night when pH is lowest.
How much kalk powder per gallon?
Kalkwasser saturates at roughly 2 teaspoons of calcium hydroxide per gallon of RO/DI water. Adding more will not dissolve and can clog your doser. Mix, let it settle, and dose only the clear liquid.
Will kalkwasser raise my pH?
Yes, dosing kalk raises pH, which is often a benefit in tanks with low pH. Dose gradually and monitor, since adding too much too fast can spike pH and stress livestock.
