I feel that most of the problems with fish on this forum site is to do with fish being kept in alkaline tanks, if these tanks were just slightly acidic the problems would go away. In an acidic tank that is well planted the hardness takes care of itself, you don't have any nitrate build up, and you have zero ammonia, even if you accidentally over feed. Therefore your general maintenance is reduced and the fish are in a more stable environment. Less stress less disease.