RO/NF membrane preservative for long-term storage. Odor-free, does not deteriorate O-rings.


  • Prevents bacterial and fungal growth in membranes during long-term storage
  • Odor-free, does not deteriorate O-rings
  • Compatible with thin film polyamide, polysulfone, PVDF and cellulose acetate membranes
  • Certified by NSF to NSF/ANSI Standard 60 for use in potable systems

Typical Properties

  • Appearance: White, granular powder
  • Odor: Pungent, characteristic
  • Solubility in water: Complete


  • 50 lb. pails and 400 lb. non-returnable plastic drums

Safety and Handling

Store in cool, dry and well-ventiled area. Keep containers closed. Avoid breathing dust. Do not get in eyes, on skin or clothing. Wash contaminated clothes before re-use. Wash hands thoroughly after handling. For more information, see the Safety Data Sheet provided with this product.

Chemical Feeding and Control

The water used to prepare the solution must be free of residual chlorine or other oxidizing agents. Best results will be achieved by using RO permeate. The recommended solution for membrane preservation consists of 1 wt% C-221 in water. The solution should be circulated through the membranes in the system for at least 15 minutes to ensure even mixing and distribution. Ensure that the membranes are fully immersed during shutdown by closing any valves that would allow drainage. This solution can be used as membrane preservative for up to 1 year. Before putting the system back online, flush membranes with feed water for at least 30 minutes to displace the storage chemical from the membranes.