Aquarium salt mix calculator

Precisely calculate exactly how much reef salt you need to achieve your target salinity for new aquarium setups or regular water changes.

Salt brand

Each brand has a different grams-per-litre density. This changes the exact amount required to reach your target.

Water parameters

Tank volume

4 L 2000 L

Current salinity

ppt

0 ppt 40 ppt

Target salinity (Natural reef: 35.0 ppt)

ppt

20 ppt 40 ppt

Total salt required

-- grams

Kilograms -- kg

Always mix salt in a separate container with RO/DI water. Never add dry salt directly to an aquarium with livestock.

Important note on accuracy

Salt requirements are guidelines and may need adjustment for mix moisture and water temperature.

For reliable results, heat RO/DI water to 75–78°F (24–26°C), check salinity with a calibrated refractometer, and add salt gradually until the desired level is reached.

How to measure salinity using a refractometer

How to properly mix reef salt

Step 1: Start with RO/DI water

Fill your mixing vessel with pure RO/DI water. Tap water introduces phosphates, nitrates, and metals your reef can't buffer.

Step 2: Heat before dosing

Bring the water to 24–26°C (75–78°F) first. Warm water dissolves salt faster and prevents cold precipitation.

Step 3: Aerate for 24 hours

Run a powerhead and airstone for at least 24 hours before testing salinity. Use a calibrated refractometer for accuracy; never rely on a hydrometer.

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