Calcium Ultimate Range
In Balance
If calcium levels are too high in your reef tank, it can lead to imbalances with other important parameters (like alkalinity and magnesium), and in extreme cases, can cause precipitation of calcium carbonate. Here's how to handle and prevent high calcium levels:
Ideal Calcium Range for Reef Tanks
380–450 ppm is generally considered ideal.
Anything over 500 ppm is typically considered too high.
Causes of High Calcium
Overdosing calcium supplements
Imbalance in your 2-part dosing (calcium and alkalinity)
Improper use of kalkwasser or calcium reactors
Infrequent water changes
What to Do If Calcium Is Too High
1. Stop Dosing Calcium Temporarily
Pause any calcium additives or 2-part dosing involving calcium until levels return to normal.
2. Check and Balance Other Parameters
Alkalinity: Aim for 8–11 dKH.
Magnesium: Aim for 1250–1350 ppm.
Balancing magnesium often helps stabilize calcium and alkalinity.
3. Partial Water Changes
Do a series of water changes using salt mix with lower calcium concentration to gradually lower levels.
4. Allow Natural Consumption
Corals, coralline algae, and other invertebrates will consume calcium over time. Just stop dosing and monitor levels daily.
5. Review Dosing Equipment
Calibrate dosing pumps if you use them.
Make sure you’re not double-dosing through both a calcium reactor and a 2-part dosing regimen.
Prevention Tips
Test frequently: Use reliable test kits or digital testers for calcium, alkalinity, and magnesium.
Keep logs: Track dosing and test results to spot trends.
Balance dosing: Ensure calcium and alkalinity are dosed in sync.
Consider automated dosing controllers for better precision.