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For what is silt density index (SDI) used?

Silt Density Index Testing

Silt Density Index FAQ

SDI is used to determine if and what kind of prefiltration will be needed for an RO system.

  • SDI of <5: No prefiltration is necessary.
  • SDI of 5-10: A media (sand-type) filter is required.
  • SDI of >10: A 2-stage media filtration is necessary - possibly with the aid of coagulants or settling tanks.