Calculators
Magnesium

Magnesium dosing calculator

How much to dose to raise your reef tank's magnesium. Magnesium comes first — it is what lets your tank hold calcium and alkalinity. Every figure is sourced.

Unit

Use net water volume — subtract ~10–20% for rock and sand.

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Correct magnesium before chasing calcium and alkalinity — it is what lets your tank hold them.

New to this? The guide explains the why: how to raise magnesium.

This is the dose for right now. Reef Stability learns how fast your tank actually uses alkalinity, calcium and magnesium, and tells you whether your daily dose is keeping up — or when to leave it alone.

Coming soon to the App Store