GENERAL HARDNESS

General hardness (GH) is a measure of all minerals, including carbonates molecules. If you subtract the KH (carbonate hardness) from the GH (general hardness), you will have an estimation of the mineral content in the water. Water with a higher mineral content is commonly called hard, while that with a low mineral content is called soft. In nature, minerals such as calcium and magnesium (which come from calcium and magnesium carbonate) have no effect on the pH of a system. As a result, it is possible to have very hard water (water of high mineral content), but have very little carbonate activity Eand consequently, a lower pH. As is the case with carbonate hardness, a general hardness of over 300 PPM is harmful to Arowana.