GE GXRM10G output is higher TDS than input, after replacing all filters -- whaa?
I recently replaced filters and membrane on my GE GXRM10G undersink RO system. After a couple of weeks I checked TDS, expecting product water to show a tenth or so of feed water TDS level, but product water actually measures higher than feed water! Product (output) water is 775 ppm; source water is 660 ppm. And we're seeing a slight green color in the product water that we hadn't seen before. I did the filter job myself, using the correct new GE filters. I'd changed pre and post filters before, but this was the first time I'd changed the membrane, which was at least 6 years old. I was careful, and things seemed to go smoothly, but I guess I could have screwed up somewhere. Thanks in advance for any assistance you can provide.