Salinity

Definition

Salinity is the concentration of dissolved salts in water, expressed as parts per thousand (ppt) or specific gravity (SG).

Practical use

Reef target: 35 ppt = 1.025-1.026 SG. Brackish: 5-15 ppt. Freshwater: 0 ppt. Measure with a refractometer (calibrated monthly with 35 ppt solution); hydrometers drift unreliably.

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