Used RO unit question

[dawaterboy]

I traded an old light strip I used for fw for an r/o unit. My tds meter is reading 70 on the clean side. My tap water in near 400. Do I need a new membrain or could it just be the other filters. I got two different stories from the guy about why he was getting rid of it so I'm really not sure how old any of the filters are.

[ERICinFL]

I'd go ahead and replace the filters. If you don't have a DI cartridge, add one of those too. That should get your TDS down to zero. How many stages does it have?

[dawaterboy]

It's a two stage. After I let it run for a few hours my reading was down to 30. I know it's not 0 but thats a long way from over 300.