KH and alkalinity are important for plant growth and resisting pH swings in your aquarium<\/a>, as we’ll learn below.<\/p>\n\n\n\n Alkalinity is the ability of water to resist changes in pH. Alkaline substances have a pH greater than 7 and acidic ones have a pH less than 7.<\/p>\n\n\n\n The carbonates dissolved in water give alkalinity its basic characteristics.<\/p>\n\n\n\n Without alkalinity, your aquarium water<\/a> would experience pH swings, which could cause stress for your fish. pH is also important for achieving healthy aquatic plant growth.<\/p>\n\n\n\n Not quite. Alkalinity is about resisting pH swings, whereas an alkaline solution has a pH of above 7.0.<\/p>\n\n\n\n An aquarium with a high degree of alkalinity will cause the pH to be above 7.0, which causes it to become “alkaline.” This is why many people in the fishkeeping hobby often use the two terms interchangeably.<\/p>\n\n\n\n When people say they have hard water they are usually referring to what’s called “general hardness.” This is the concentration of calcium and magnesium ions present in your aquarium.<\/p>\n\n\n\n General hardness is also shortened to GH when measuring hardness in parts-per-million (ppm) or dGH when measuring in degrees of hardness.<\/p>\n\n\n\n But there is another form of water hardness<\/a> aquarists often talk about called carbonate hardness.<\/p>\n\n\n\n Carbonate hardness, or KH, measures the concentration of carbonate and bicarbonate bases in your water sample. This is also what people often confuse with alkalinity.<\/p>\n\n\n\n These carbonates are the most prevalent and important bases that are part of an aquarium’s total buffering system. They soak up excess hydrogen ions that would otherwise cause the pH to decrease.<\/p>\n\n\n\n Similar to general hardness, carbonate hardness is usually measured using KH or dKH.<\/p>\n\n\n\n![\"\"](\"https:\/\/rootedtank.com\/wp-content\/uploads\/2021\/11\/Feature-images-3.jpg\")
<\/figure>\n\n\n\nWhat is alkalinity?<\/strong><\/h2>\n\n\n\n
Is alkalinity the same as alkaline water?<\/strong><\/h2>\n\n\n\n
What does it mean to have hard water?<\/strong><\/h2>\n\n\n\n
What is carbonate hardness?<\/strong><\/h3>\n\n\n\n
dGH or dKH value<\/strong><\/td> GH or KH parts-per-million (ppm)<\/strong><\/td><\/tr> 1<\/td> 17.9<\/td><\/tr> 2<\/td> 35.8<\/td><\/tr> 3<\/td> 53.7<\/td><\/tr> 4<\/td> 71.6<\/td><\/tr> 5<\/td> 89.5<\/td><\/tr> 6<\/td> 107.4<\/td><\/tr> 7<\/td> 125.3<\/td><\/tr> 8<\/td> 143.2<\/td><\/tr> 9<\/td> 161.1<\/td><\/tr> 10<\/td> 179.0<\/td><\/tr> 11<\/td> 196.9<\/td><\/tr> 12<\/td> 214.8<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n What’s the difference between general hardness and carbonate hardness?<\/strong><\/h2>\n\n\n\n