eyou Posted November 17, 2008 Share Posted November 17, 2008 So i did some measurements of my water. Tap: 240ppm RO: 50ppm DI: 8ppm Does that seem about right from goign from tap to RO? i thoguht the RO reading was a little high, and then of course the after the DI its not 0 ppm. The RO membrane was 100 gpd, and i got like a cheap $100 kit from ebay. Ive used these before and have gotten 0 ppm, but i can't get that quality right now (before the DI chamber was bigger and the RO membrane was 75 gpd) Do you think adding another DI Unit would get the water to 0ppm (the cheaper solution)? Or would I have to get a smaller/slower membrane for the ro unit? Thanks! Link to comment
vg30et Posted November 17, 2008 Share Posted November 17, 2008 Probably cheaper in the long run to get a better RO membrane. I was getting ~30PPM from my cheap RO unit and it would exhaust my DI cartridges pretty quickly. I switched to a Filmtec75GPD RO membrane (~$35) and my readings are now: Tap: 340ppm RO: 8ppm DI: 0ppm Also check your restrictor valve to make sure it's tuned right otherwise you may kill your new RO membrane. Link to comment
eyou Posted November 17, 2008 Author Share Posted November 17, 2008 were you using a 75 gpd membrane before and it was just a cheaper brand? or did you actually go down in gpd rating? Link to comment
AZDesertRat Posted December 1, 2008 Share Posted December 1, 2008 Your membrane is only 70% efficient! Thats not good at all, it should be 96-98% efficient at least. DI will never last with a TDS of 50 going in and will probably never get to 0 TDS. You should be seeing a RO only TDS of about 5 not 50. The cost of a couple DI replacements is equal to the cost of a new membrane, I would opt for the new membrane which will extend the life of the DI and get you 0 TDS. A very accurate rule of thumb says, "For every 2% you increase the RO membranes efficiency you DOUBLE the life of your DI resin". This is true so imagine what going from 70% efficiency to 96-98% rejection will do for you. Link to comment
Scott Riemer Posted December 1, 2008 Share Posted December 1, 2008 Like everyone else says, the problem is your RO membrane. It should be a lot more efficient. Have you tested your water pressure? Link to comment
AZDesertRat Posted December 2, 2008 Share Posted December 2, 2008 Water pressure has very little to do with rejection rate or removal efficiency. It will affect GPD output though as does water temperature. Link to comment
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