View source for DGH

{{Short description|Unit of water hardness}}

{{Lowercase title}}

{{technical reasons|DGH|other uses|DGH (disambiguation)}}

{{No footnotes|date=August 2024}}

'''Degrees of general hardness''' ('''dGH or °GH''') is a [[Units of measurement|unit]] of [[Hard water|water hardness]], specifically of general hardness. General hardness is a measure of the concentration of [[divalent]] metal ions such as [[calcium]] (Ca<sup>2+</sup>) and [[magnesium]] (Mg<sup>2+</sup>) per volume of water. Specifically, 1 dGH is defined as 10 milligrams (mg) of [[calcium oxide]] (CaO) per litre of water. Since CaO has a [[molar mass]] of 56.08 g/mol, 1 dGH is equivalent to 0.17832 [[mmol]] per litre of elemental calcium and/or magnesium ions.

In water testing hardness is often measured in parts per million (ppm), where one part per million is defined as one milligram of [[calcium carbonate]] (CaCO<sub>3</sub>) per litre of water.  Consequently, 1 dGH corresponds to 10 ppm CaO but 17.848 ppm CaCO<sub>3</sub> which has a molar mass of 100.09 g/mol.

== See also ==
{{Portal|Water}}
* [[Carbonate hardness]]
* [[Hard water]]
* [[dKH]]

== References ==
* {{Cite web |url=https://www.thekrib.com/Plants/CO2/hardness-larryfrank.html |title=Water Hardness |date=1997-12-16 |access-date=2011-11-04 |website=The Krib |last=Frank |first=Larry |archive-url=https://web.archive.org/web/20181024035241id_/https://www.thekrib.com/Plants/CO2/hardness-larryfrank.html |archive-date=2018-10-24 |url-status=live}}
* {{Cite web |url=https://www.cactus2000.de/de/unit/masswas.php |title=Wasserhärte [de] / Dureté de l'eau [fr] |date=2022 |access-date=2009-01-23 |website=Cactus2000 |last=Krüger |first=Bernd |archive-url=https://web.archive.org/web/20210222031923id_/https://www.cactus2000.de/de/unit/masswas.php |archive-date=2021-02-22 |url-status=live |language=de, en, fr |trans-title=Hardness of water}}

[[Category:Units of measurement]]
[[Category:Water chemistry]]

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