Silt Density Index
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      What does the SDI filter paper color mean?

      Silt Density Index Testing

      Silt Density Index FAQ

      Filter paper coloration after the SDI test:

      1. Slightly yellow – The possible problem could be the presence of iron and/or organics in feed water. Check the source.
      2. Reddish-brown – Positive indication of the presence of iron in feed water. Take corrective steps for the removal of iron.
      3. Gray – Indicates the presence of carbon fines. Check the carbon filter, remove carbon fines.
      4. Particles present on the filter paper – Check the cartridge filter and the filter elements.
      5. Dark Black – If the color dissolves in the acid, it indicates the presence of manganese in the water.