I got a used 5 stage rodi and when i intially got the plumbing figured out i was getting an output tds of 70ish. I bought a new membrane and new media and still got about 70. I figured something weird was good on so i tested tds right after the membrane and its only about 5-6ppm. So my question is what could be going wrong after the member. Either the di or carbon block are adding almost 65ppms. Any ideas why this is happening? I've seen people say it could be bad di resin but i doubt that the last resin and this brand new resin were both bad.