I just changed over from a single handheld TDS meter to a dual. I hooked it up after particulate, carbons, and RO. Going in and out of DI canisters. When I first turned it on it it registered 003 and after DI 000. After a minute it registered 000 on both sides of the DI! My particulate filer is new but the other filters, including the RO membrane is is over 1 1/2 years old. I usually run about 20 gallons of water per week.
Our water in Eugene, out of the tap is typically 40-50ppm. Can an RO that is this old be that clean or is it that the meter is off? I read on the instructions that it is calibrated at the factory for 350ppm. Should I consider re-calibration? I can re-calibrate this model. I have not heard of others having this problem.