Best Colloidal Silver Water - #1 Safe Natural Antiseptic Best natural remedy for Athlete's foot and finger and toe nail fungus. Silver Excelsior Serum (pictured above) is the best chelated silver water (most potent form of colloidal silver water.) It is not 15, 30 or 45 parts per million but 4,000 parts per million (PPM) chelated silver concentrate!