I just finished building and testing my frankenstein RODI system. First problem I noticed was I had reversed the brine and clean lines on both membranes but I reversed that and fixed it. Noticed that with my TDS meter (not pictured but now added to the white teed clean output line from the membranes). I let my membranes flow (teed into the drain) for a while to see what my ppm TDS settled out on and it actually only dropped to mid 20's. With the second membrane flushing (and therefore bypassed) I get a TDS of low teens. I realize putting brine into my second membrane will raise my TDS out of my averaged output, but I was surprised at how high it was. Should I worry about 20 TDS coming out of my RO and into my 3 part DI system? Seems like I would use lots of resin, no? My PSI was 80 by the way. Perhaps its too high? I do get 0 ppm on my DI output, but worry something is wrong that will cost me lots of resin.