What Is GH?
When a fish is said to like hard or soft water, the GH is what they’re referring to. Unlike pH, it’s not an abbreviation for a crazy equation, but short for General Hardness. Much like pH and KH, however, it measures the number of specific ions in the water – this time, magnesium and calcium. And, again, like KH, it’s measured in degrees; dH (or degrees of hardness) or dGH (degrees of general hardness.)
Generally, unless you’re experienced with water, don’t mess with GH or KH. They, usually, all impact one another and work together to make up the parameters of all water. Tampering with one will usually inadvertently lead to tampering with another and will alter your pH as well.
Although I say this in a lot of places on the site, I think it’s better to just leave sleep bicarbonates lie. But seriously, don’t tamper with it unless you absolutely have to or you really want to give yourself another chore. There’s usually not a need.
Examples of GH
Everything has a GH. It’s measured on a scale of ppm or dGH and can go from 0 to, well, infinity I’d assume. Although most water falls under 500 ppm.
According to one study, most of the east and west coats have softer water while those in the middle of the US tend to have harder water.