Already blocked today?! When a soccer player intercepts a shot, it is called “blocking”; when a bird of prey settles down, the hunter calls this “blocking” and when a coating has formed on a membrane, it is “blocked.” Such a BLOCKING can be caused either by scaling or fouling and is not always reversible. In the case of a membrane covered with calcium carbonate, rinsing with acid helps; if you are struggling with sulphates, try complexing agents (chemical compounds such as chloride ions). If your membrane is damaged by fouling, you can only stop the process by disinfecting, but not stop it.