Post use, the membrane should be rinsed with water after testing and stored in clean water if the storage duration will be less than 24 hours. If the membrane is rinsed with water and expected to be stored for longer than 48 hours, it is recommended to use a 1% sodium metabisulfite (SMB, chemical formula Na2S2O5) to prevent bacterial growth from occurring. Periodically inspect the membranes for biological growth. If the preservative solution is cloudy you need to replace it. Renew the preservative solution every month.