here's what the box says " For best results, DO NOT turn off UV Sterilizer or Ozonizer. Continuation of Protein Skimming is recommended but may require adjustment.
Due to Increased biological digestion of organic solids we recommend increasing your O2 levels by the addition of airstones prior to and during treatment.
No need for Water changes or Removal of Carbon Filtration. "
also read about it here
http://www.marinedepot.com/Ultralife...FIMERM-vi.html