My unit is a 4 stage. I think filter change is needed and due. So, need to do that. But my incoming TDS is pretty low like 5 and outgoing is 0. My water pressure is good to and its at least 60psi. I will get one hand held one as the inline one is not helping much.How many stage RODI system is it? What PSI does the unit run at while producing water? When was the last filter change? What is your incoming tds? I’d also suggest to buy a hand held tds meter. The inline ones are notoriously inaccurate. The hand held ones are not expensive and allow you to test at different points. Do you know the tds after the membrane?
All of these things will help pinpoint where the issue is at. [emoji4]