Water chemistry (Water Hardness)

Water Hardness
General Hardness, or gH as it is also known, is primarily the measure of calcium (Ca++) and magnesium (Mg++) ions in the water. GH is commonly expressed in parts per million (ppm) of calcium carbonate (CaCO3) or degrees hardness (dH). Water hardness follows these guidelines: 0 - 4 dH, 0 - 70 ppm : very soft4 - 8 dH, 70 - 140 ppm : soft8 - 12 dH, 140 - 210 ppm : medium hard 12 - 18 dH, 210 - 320 ppm : fairly hard18 - 30 dH, 320 - 530 ppm : hardOnce again each fish has a preferred gH, and if u can provide this a close as possible, then your fish will live a much happier life.