SRC MCC-3, or Membrane Cleaning Compound “#3”, is used for iron fouling and is not included in the Membrane Cleaning Chemical kit. If your System’s RO Membrane Element is fouled with rust from iron piping, then SRC MCC-3 may be used for its effective removal. Note that a rust-fouled RO Membrane may not be recoverable, as rust not only fouls the element, but also damages the element’s surface. Cleaning procedure is mentioned in the System’s Manual and on the MCC-3 package