Yes, I have a Spectrapure. The unit has in line TDS meters after every stage. I am at 98% efficiency when timed and all tds out are reading 0. Handheld TDS reads 0 from bucket. Which is not strange considering the Sediment and Carbon are changed every 3 months, I have a box of 60 each I bought ages ago, the Membrane was changed two years ago, the maxcap and silica buster were changed a year and a half ago. I usually get 5 years out of the membrane and 2 to 3 years out of the silica buster and maxcap. I have had this unit for 16 years now. I can rule out that as the issue. Now if I had a BRS unit or one of those horrid aqua craps then yes I would be worried. My salt mix maybe? Everyone is out of Nyos even saltwater aquarium crooks dot com. So I have to run up to Petco and see about picking something else up.