"Fine filter wool • Synthetic residue-free filter wool. • For freshwater and saltwater. • Washable. Product description JBL Symec is a synthetic filter floss which does not release any harmful substances into the water. It is suitable for use with both mechanical and biological filtration systems in either freshwater or saltwater aquariums. JBL Symec can be used on its own or in combination with any other standard filter material. Use Rinse JBL Symec thoroughly in warm water before use. Fluff the material up well before placing loosely in the filter to avoid the filter clogging up again too early. "