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Check Your Tank's Salinity
Enter either number and the other one updates instantly – no charts, no guesswork.
e.g. 1.025
=
parts per thousand (ppt)
Calculated at the standard 25°C / 77°F reference used by most aquarium hydrometers and refractometers. For an accurate reading, test once your sample is close to that temperature, or use a refractometer/hydrometer with automatic temperature compensation (ATC).
Typical targets: most reef tanks with corals and inverts are kept close to natural seawater, around 1.025–1.026 SG (33–35 ppt). Fish-only tanks can often run a little lower, around 1.020–1.023 SG (26–30 ppt). Always match the specific needs of the livestock you're keeping – check individual care guides in the Coral Glossary or ask our team if you're unsure.
Natural Seawater
1.026 SG / 35 ppt
Reef Tank Target
1.025–1.026 SG
Fish-Only Tank
1.020–1.023 SG
Quarantine / Hypo
1.009–1.011 SG