Talk:DGH

GH does NOT include KH.
KittyKat insists that: "with regards to aquaria, GH tests measure KH and metal ions, not only the metal ions", but this is incorrect. With regards to aquaria, or for any other use, GH is solely a measure of the hardness-causing cations (Mg, Ca) in the solution, and does not, in any way, attempt to measure the carbonate and bicarbonate anions (carbonate alkalinity). Those anions are measured by KH.

Citations:

My API KH & GH Test Kit says:

"What is Carbonate Hardness (KH)? Carbonate hardness (also known as alkalinity) is the measure of carbonate (Co32-and bicarbonate (HCO3-) ion concentrations dissolved in water."

"What is General Hardness (GH)? General hardness is the measure of calcium (Ca2+) and magnesium (Mg2+) ion concentrations dissolved in water."

See also: http://www.thekrib.com/Plants/CO2/hardness-larryfrank.html "General Hardness (GH) measures the cations (+ charge); for calcium and magnesium." "Carbonate Hardness (KH) Refers to only the bicarbonate, and carbonate anions(-charge); it does not measures the sulfates and other anions." — Preceding unsigned comment added by Turjan (talk • contribs) 04:51, 4 November 2011 (UTC)

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GH does not measure anything. It is a scale of measurement based on the amount 10mg of CaO per liter. CaO has a molecular weight of 56.08. KH is a scale based on 10mg of CaCO3 per liter. CaCO3 has a molecular weight of 100.9. Thus 1 dGH is equal to 100.09 /56.08 = 1.7848 dKH See https://www.cactus2000.de/uk/unit/masswas.shtml

Also Carbonate hardness is known as calcium alkalinty but it is NOT the same thing. They are only approximately equal. A B McDonald (talk) 17:59, 10 November 2017 (UTC)