Strontium (Sr)
Strontium is a trace element that contributes to the calcification of corals. It is consumed slowly and must be replenished in intensive reef aquariums.
Detailed explanation
Strontium works together with calcium in the formation of the coral skeleton. The skeleton of stony corals is made of aragonite which incorporates small quantities of strontium into its crystalline structure.
In an aquarium with many SPS the consumption of strontium is measurable. High-end Balling systems include strontium in the solutions (Red Sea Foundation A, Triton Core7). Anyone who prepares Balling by hand must add it separately.
The concentration in nature is approximately 8 ppm. In the aquarium we aim for the same value. Many sea salts already contain it in the correct proportion and regular water changes are enough to maintain it.
It's not a parameter to obsess over. Regular water changes and good sea salt cover the needs in most cases. Only very intense reef aquariums with massive SPS growth require dedicated supplementation.
Reference values by aquarium type
| Aquarium type | Recommended range |
|---|---|
| Marine (reef) | 6 - 10 ppmThe natural value of sea water is approximately 8 ppm |
How it is measured
Only via ICP analysis. There are no reliable drop tests for strontium.
What happens when it is too low
Slowed coral growth. Fragile skeletons. Rarely an isolated problem: it usually also indicates calcium deficiencies.
What happens when it is too high
Above 15 ppm may interfere with calcification. Rare if quality sea salts are used.
Coralia Lab monitors this parameter with AI diagnostics. Tank Score alerts you when a value moves outside the recommended range for your aquarium.
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