When the reading is higher
Confirm calibration and temperature compensation, then review evaporation and top-off behavior.
Reef aquarium salinity guide
Many reef systems are maintained near natural seawater, around 35 ppt or 1.026 SG at 25°C. Track repeated readings and recent care instead of treating one number as a diagnosis.
When the reading is lower
Confirm calibration, recent water changes, top-off volume, and salt-mixing procedure.
Units and review
ppt / specific gravity · Content reviewed 2026-09-02. Verify urgent livestock, dosing, and treatment decisions with qualified sources and product labels.