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Chemistry Chemistry
Salinity
The total dissolved salt content of saltwater - typically measured as specific gravity (SG) or parts per thousand (ppt).
Unit: ppt or SG Code: SALINITY
📖 Overview
Natural ocean salinity is 35 ppt (SG 1.026). Reef aquariums target this precisely; fish-only saltwater tanks can operate slightly lower (SG 1.020-1.025). Precise salinity control is essential - variations of even 0.001 SG stress sensitive corals.
🧪 Testing Methods
Refractometer (most accurate, requires calibration with pure water). Hydrometer (cheaper, less precise). Digital salinity monitors (top-tier reef systems).