High TDS

[Gools]

Just upgraded my membrane from 50gpd, to 75gpd along with restrictor. I run DI. but I can't get a 0 TDS. DI is colour changing and still shows half good, it is the same DI that was in when I had my 50 membrane. But now I'm getting a TDS of 004. I always got a reading of 0 with my 50gpd. Not sure why I can't get back there. i should add I flush my membrane 5min once a week.

If you have any suggestions would be great. Thanks