dH
German hardness [degrees]; unit of water hardness
There are several differently defined national hardness units, e.g. fH (French hardness etc.).
For this reason, hardness is nowadays better expressed in mol/l of the corresponding ions.
| °dH | mval/l | mmol/l | ||
|---|---|---|---|---|
| German degrees | 1 °dH = | 1 | 0,357 | 0,1783 |
| mval/l Alkaline earth ions | 1 mval/l = | 2,8 | 1 | 0,50 |
| mmol/l Alkaline earth ions | 1 mmol/l = | 5,6 | 2,00 | 1 |