How do you do a TDS test?
Here are the steps to test if your RODI unit is functioning properly and removing the correct amount of TDS:
1. Fast Flush your unit for 10 minutes.
2. Make RODI water for 10 minutes
3. Take a TDS reading of your Tap water! (Now clean the TDS meter probes)
4. Take a TDS reading of your RO Only water (Before the DI). This reading should be less than 5 ? 10% of the tap water reading. (If your TDS reading is more than 10%, replace your membrane.) Clean TDS meter probes.
5. Take a TDS reading of your RODI water. It should be close to ZERO! If this is a new DI filter and your meter reads higher than ZERO, your TDS meter is WRONG!!
FYI: A quick and easy test to determine if your DI is exhausting too quickly is calculated as follows: Example: If your tap water TDS is 200 PPM your RO only water after the membrane, should be around 10 PPM. Then divide 1200 by this 10 PPM equals about 120 gallons of RODI before your DI resin will exhaust. **This is for a 10? refillable cartridge. The In-Line DI filters only last HALF as long. The 20? refillables will last TWICE as long.