Calcium (Ca) Calculator - Tools & Calculators
Calcium (Ca) Calculator
Estimate Calcium (Ca) level from General Hardness (GH) and Magnesium (Mg).
How do I calculate calcium in my aquarium water?
Why is calcium important for aquariums?
Calcium (Ca) is one of the two main components of general hardness (GH), alongside magnesium. It is essential for shell and exoskeleton development in snails, shrimp, and crayfish. Many aquatic plants also require calcium for cell wall structure and nutrient transport. Insufficient calcium leads to soft shells, molting problems, and poor plant growth.
How the calculation works
General hardness (GH) is the combined concentration of calcium and magnesium ions. If you know your GH and magnesium level, you can calculate calcium:
Ideal calcium levels
| Tank type | Ca (ppm) |
|---|---|
| Planted tank | 20–40 ppm |
| Shrimp tank (Neocaridina) | 30–50 ppm |
| Caridina shrimp | 20–30 ppm |
| Snails (nerite, mystery) | 40–70 ppm |
Calcium to magnesium ratio
The ideal Ca:Mg ratio is typically 3:1 to 4:1. This balance ensures optimal mineral uptake for both plants and invertebrates. Imbalanced ratios can cause nutrient lockout in plants and shell problems in shrimp.
How to raise calcium levels
- Calcium chloride (CaCl₂): Fast-acting, raises Ca without affecting KH
- Calcium sulfate (gypsum): Gentle, adds Ca and sulfur
- Crusite shells, cuttlebone: Slow-release, also raises KH and pH
- GH remineralizers: Add both Ca and Mg in balanced ratios