Results for “hydrometer”

hydrometer

Instrument used to measure the density of a liquid, normally in the form of specific gravity. Can be inaccurate should calcium deposits form on the swing arm, for example, and generally less reliable than a refractometer.

refractometer

Instrument used to measure salinity or specific gravity via the refractive index (basically, the degree that light bends when shined through something) of a liquid. Most models are designed to measure sodium chloride or brine solutions and not seawater which contains a more complex range of salts and minerals, but usually more accurate than a hydrometer nevertheless.

specific gravity

Ratio of the density of a liquid to the density compared with pure water. Often used to deduce the salinity of aquarium water and measured using a hydrometer or refractometer.

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