New Dow membrane poor rejection

[beyarbrough]

I just replace my one year old membrane in an attempt to lower DI resin usage. I was getting 6 ppm from 130 ppm water so roughly 95-96% rejection. I replaced the membrane with the same brand and model Dow Filmtec BW60-1812-75. Now I'm getting 8 ppm filtered, or about 94% rejection. I went ahead and let it run for two days to clear anything that may be in it from manufacturing but the tds has not changed from 8. Now I'm not very happy. Old membrane is back in now still producing 6 tds. I'm not sure if I should ask for a replacement, or a refund and get a different brand. What do you guys think?

 

[beyarbrough]

Well I asked for a replacement and the company I purchased the membrane from said to run it for another week and TDS should go down. Does this sound right? I don't want to waste all that water just to get TDS down. Should I be more aggressive with my request for replacement?

 

[beyarbrough]

Bump. The company seems unwilling to replace the filter, but I'm not sure if what they are telling me is true or not. I don't want to demand a refund if there truly is nothing wrong with the membrane. Any advice?

 

[cromag27 Verified Sponsor]

Take it apart and make sure it's seated properly. also, are you measuring tds of tap water and after membrane, to calculate rejection rate? What is your psi?

 

[sundog101]

This may help. Pressure and temperature can affect performance.

 

[beyarbrough]

Thanks for the replies. It was definitely seated properly. I am checking tds of water before it goes into the membrane and right after the membrane for rejection. The problem is the tds from the new membrane never got to where my old membrane was. I could take the new membrane out and put the old one back in and immediately have lower tds water. The company did agree to send a new membrane and it should be here next week. Thanks!

 

[beyarbrough]

Water pressure is 60 psi.