During normal operation, RO membranes can become fouled, which greatly reduces the efficiency of the system. Deposits build up on the membrane until they cause a reduction in permeate flow and loss in salt rejection. The effects of fouling can lead to poor water quality, loss in production, unscheduled downtime and membrane replacement. A regular maintenance and cleaning program can provide return on investment (ROI) results ranging from 100 to 250% by maintaining low pump output pressures and extending the membrane's life. Elements should be cleaned whenever the normalized permeate flow rate or salt rejection decreases by 10-15% or the differential pressure increases by 10-15% from the original baseline data.

MembraneClean MC 33 Alkaline RO Cleaner should be fed via a closed feed system. A closed feed system is defined as a system in which fluid is moved from a closed storage vessel into a treated media without exposure to the atmosphere except through normal venting or pressure relief devices.

Cleaning solutions should be made up with chlorine-free water to give a 2.0 - 2.5% solution of MembraneClean MC 33 Alkaline RO Cleaner. It is sometimes possible to monitor the progress of membrane cleaning by the "pick-up" of hardness salts in the cleaning solution.