Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Both GH and KH are commonly reported in either of 2 formats when you are talking about aquariums, and most people can relate to both.
German degrees of hardness, abbreviated dGH and dKH.
Parts per million, abbreviated ppm, and you need to specify GH or KH.
There are 17.9 ppm in one German degree of hardness.
For a really quick translation, I usually think of that as 20.
So if the GH is reported as 100 ppm, I would instantly say, Oh, not too far off 5 dGH. Fairly soft water. But if I use the calculator it is closer to 5.6, which is still fairly soft.
Test strips usually show ppm.
Test tube and reagent tests usually result in German degrees of hardness.