WATER LINE: Products such as suntan lotion, underarm deodorant, women's makeup, and even body oils and dirt, can cause a water line (scum ring) to form at the surface of the water, along the perimeter of the pool. This will happen from time to time, even in pools that posses continual water circulation, proper filtration, proper water chemistry, sufficient chlorine (or its alternative) levels, and routine shocking. An effective treatment for a water line (scum ring) is an ENZYME CLEANER. An enzyme will break down any of these products, body oils, or dirt into their simplest form-liquid. Initial foaming will occur after adding the enzyme. This foam is good-it is a signal that the enzyme is eliminating the water line (scum ring) and breaking it down into water. The result will be the removal of the water line (scum ring), restored water clarity, and relief on the filtration system. Many pool owners wisely add an enzyme cleaner as part of their routine maintenance schedule.