I`ve replaced my 100 GPD RO membrane today for a DOW FILMTEC 75 GPD RO membrane with matching flow restrictor. I also replaced the sediment filter, carbon filter and the DI cartrige had been changed about 5 days ago with Fauna Marin MB20 mixed bed resin.

Before changing the RO membrane, sediment and carbon filters I was getting a TDS reading of 2ppm. Now after replacing all filters I get a reading of 5ppm ( 11ppm after ro membrane and 5 after DI ) TDS entering the RO unit is 175 ppm.

Also when I flush the membrane TDS goes down to 3 or 4ppm and when I close the flush valve it goes back to 5ppm.

The unit has been working for over 2 hours so I think that new membrane fluid is not the issue.

Its also producing more water than it should! 1 gallon is 15.5 minutes.


Any thoughts about what might be wrong??