Is my RO membrane not doing its job?

kv69 · Jan 9, 2014

Okay so my water is 40 PPM. Coming out of the membrane chamber its 25 ppm? So that means my DI has to take out the other 25ppm. It exhausts so quickly... Only 50 gallons or so???

Does this sound right to you guys?

Thanks in advance..

tektite · Jan 9, 2014

Most good membranes have a rejection rate of 98%+, if your incoming tds is 40, a good membrane should knock that down to almost zero.

kv69 · Jan 9, 2014

After some quick research, I have found that I have a 37 percent rejection rate. That is not good. Thank you Tektite you are correct and I have a obviously crappy RoDI. Ebay model. I only use about 15 gallons per week. I checked all connections made sure membrane was seated and retested. Still the same.

The membrane is less than 12 months old with very little usage. Sent a email to the vendor, we will see what they say.

As of now I guess I'm in the RoDI market.

By my calculations this membrane should last at least three years and I shouldn't be changing my di resin after running 50 gallons of 0 TDS water.

Lesson learned again, ask more questions and buy quality products..

benny z · Jan 9, 2014

pick up a filmtec membrane from air, water, ice. should be the only thing you need. maybe stock up on prefilter and carbon blocks while you are at it.

cdness · Jan 9, 2014

Yeah you get what you pay for. There are many good suppliers for RODI stuff from BRS, Air Water Ice, Spectrapure, etc. Personally I bought my last membrane from Spectrapure due to the fact that they test and certify their rejection rate. The others are nominally rated and one out of so many are tested for quality. Spectrapure tests ALL of their certified membranes so you know you are getting what you pay for.

With that said, I ran a base BRS unit with the filmtec membrane for more than 5 years without issues. It treated me well and I have nothing bad to say about their systems.

kv69 · Jan 9, 2014

Okay I'm ordering a filmtec now and we will see if that works, it looks as if this is the "original" everyone has copied..

Could be crappy membrane.. Hopefully...

Thanks benny z