Karbonathärte (KH) im Riffaquarium erklärt

Dieser Guide deckt alles ab, was Sie über Alkalinity (dKH) im Kontext eines Meerwasser-Riffaquariums wissen müssen. Kein Süßwasser.

Why alkalinity matters

Alkalinity is the single most important parameter to keep stable in a reef tank. It buffers pH and provides carbonate ions for coral skeleton building. A swing of more than 1.5 dKH per day can trigger RTN in sensitive SPS corals. Test daily and dose accordingly. Two-part, kalkwasser, or a calcium reactor are common supplementation methods.

Target range

7–11 dKH is the recommended range for mixed reef aquariums. This range supports coral growth, coloration, and overall system stability. The exact ideal value depends on your coral mix—SPS-heavy tanks often run at the higher end, while soft-coral and LPS tanks are more flexible.

Condition	Range	Risk
Too low	Below range	Reduced coral growth, browning, potential RTN
Optimal	7–11 dKH	Healthy growth, stable system
Too high	Above range	Algae issues, precipitation, coral stress

How to test

Liquid test kits: Affordable but less precise. Suitable for regular monitoring.
Hanna checkers: Digital colorimeters offering better accuracy and repeatability.
ICP-OES analysis: Laboratory testing for comprehensive water analysis. Best for periodic deep checks.

Test daily or every other day when actively dosing.

How to adjust

Raising alkalinity

Calculate your daily consumption by testing at the same time on consecutive days.
Dose sodium bicarbonate (baking soda) or a commercial alkalinity supplement.
Never raise dKH by more than 1.5 units per day—slower is safer.
For long-term automation, set up a dosing pump with two-part solution.

Lowering alkalinity

High alkalinity (>12 dKH) is unusual but can be corrected with water changes using a salt mix that produces lower alkalinity. Stop or reduce dosing and let coral consumption bring it down naturally.

Häufige Fehler

Chasing perfect numbers. A stable 8 dKH is better than alkalinity that bounces between 8 and 11. Consistency beats precision.
Dosing without testing. Never dose blindly. Always test before and after adjusting any parameter.
Adjusting multiple parameters simultaneously. Change one parameter at a time, wait 24–48 hours, then test again before making further adjustments.
Using expired or contaminated test reagents. Replace test kits annually and store reagents properly.

Tipps für den Erfolg

Test at the same time each day for consistent readings—parameters fluctuate with photoperiod.
Invest in a Hanna checker for your most critical parameter—the accuracy upgrade is worth the cost.
Keep a parameter log (spreadsheet or app) to track trends over weeks and months.
Calibrate refractometers and probes regularly using certified reference solutions.
When in doubt, do a water change. Fresh saltwater resets parameters toward ideal ranges.

Häufig gestellte Fragen

How often should I test this parameter?

Test daily or every other day when you are actively dosing or adjusting. Once your dosing is dialed in and consumption is stable, testing 2–3 times per week is sufficient.

What happens if this parameter swings suddenly?

Rapid swings are far more dangerous than a slightly off but stable reading. A sudden change can trigger coral stress responses including tissue recession, bleaching, or RTN/STN in SPS corals. Always make adjustments gradually.

Should I use a controller to monitor this?

For critical parameters like this one, a continuous monitor (Neptune Trident, GHL KH Guardian, or similar) is an excellent investment for SPS-dominant tanks. It provides real-time data and alerts you to swings before they become dangerous.