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 Basic TDS Tester
 TDS Meter 3
 TDS Meter 4
 TDS Meter 4TM
 EC/TDS Combo Meter
 Waterproof pH Meter
 Waterproof ORP Meter
 TDS-EZ Water Quality
 AP-1: AquaPro (TDS)
 AP-2: AquaPro (EC)
 Conductivity Tester
 Water Quality Tester
 Dual TDS Monitor
 Dual TDS Monitor 2
 Clean Tap Monitor
 Purity Monitor
 External Purity Monitor
 FM-1: Filter Monitor
 FM-2: Filter Monitor
 PSC-150:TDS Controller
 QC-1:TDS Monitor
 In-Line Single Monitor
 Panel Mount Controller
 Dual TDS Controller
 Dual Display Controller
 Conductivity Controller
Injection Controller
TDS/EC Controller
 Precipitator 1
 Precipitator 2
 Calibration Solutions



  • If you have a filter or RO system in your home, you need to check the water it produces periodically to make sure it's working properly. The performance of RO systems and filters are measured by the amount of TDS Reduced by the filters and membranes. The reduction of TDS indicates the reduction of microorganisms and harmful non-solids such as chlorine and fluorine.

  • So be sure to check the quality of your water every month to make sure your filters or membranes are working well!

    Carbon Filters

  • Granular activated carbon filtration is the most common technology used in home filter systems. Unfortunately, these home systems are often poorly maintained. In many cases, filters are not cleaned properly, or filter elements are not changed at appropriate intervals. Over time, effectiveness declines, and in some cases the contaminants in the overloaded filter actually begin to discharge back into the water.

    RO Percentage Rejection

  • The effectiveness of an RO unit is characterized by the rejection rate or rejection percentage.
  • The rejection rate is the percent of a contaminant that does not move through, or is rejected by the membrane. Rejection rates need to be high enough to reduce the contaminant level in the untreated water to a safe level.
  • To determine the needed rejection rate, it is necessary to consider the initial concentration. For example, when the feed water contains 300 ppm total dissolved solids (TDS), the product water may have 15 to 30 ppm (95% and 90% rejection ratio respectively).
  • An RO system design is based on a certain range of feed water TDS, the percentage of rejection and percentage of recovery desired. For a given system, the higher the percentage of recovery or the lower the percentage of rejection, the poorer the quality of product water becomes. (US FDA)

    Use the calculator below to determine the percent rejection of your RO system.

    Enter the TDS level of the product water
    Enter the TDS level of the feed water

    Percent Rejection = %




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