sera KH/pH Minus (Acid Buffer)Soft water but safely Lowers pH and KH Adjusts the carbonate hardness Regulates the pH value For appropriate soft and slightly acidic water Some fish species (e. g. wild discus and angelfish) are adapted to very soft water and require these conditions in particular for reproducing. However, the water can provide too high carbonate hardness (KH), or the pH may have risen too strongly due to natural metabolism processes, also when keeping other fish