RO membrane issues.

[vikubz]

I have a Kent 3 stage to which I've added a DI stage about 5 weeks ago. The resin seemed to be changing color really fast, so I ordered a TDS meter and got the following results.

Tap water 229 ppm
RO output 90 ppm
DI output 0 ppm

So at least the DI is working, but what might be going on with the RO membrane?

It is a filmtec 50 gpd which I got new in September.

I run a 1 micron sediment filter and a .6 micron carbon block filter.

Would too much water pressure cause the membrane to be less efficient?

Thanks,
Mark

 

[poppin_fresh]

Assuming the system is set up properly it sounds like the membrane might be shot. You should be seeing less than 12 after the membrane if its working properly.

Too much water pressure can cause problems, but how much are we talking about? Water thats too warm will ruin a membrane also as will chlorine.

I would first pull the membrane out and reinstall to make sure its properly seated. If the tds is still high the membrane is probably no good. You can leave it, but you are going to use a lot more DI.

 

[vikubz]

Well, I know it's not water temp, cuz it's nice and cold.

I did let the previous carbon filter go for eight months rather than 6, so maybe some chlorine was getting through to the membrane.

I will try re-seating the membrane and see if that helps.

Thanks,
Mark

 

[AZDesertRat]

That may do the trick, check the o-rings and sealing surfaces closely too. You should only be seeing about 5 TDS from the RO only since that is a 98% rejection rate membrane. If you were using a good carbon block the chlorine should not have been enough to trash it in 8 months, a 0.6 micron block is good for 20,000 gallons of water at a 1 ppm chlorine residual.

Make sure when you are checking TDS to use a squeaky clean glass drinking water glass with absolutely no soap residue or water spots on it. Make sure to triple rinse both the glass and the TDS meter with DI water between each test no matter what and triple rinse both before putting them away so they stay clean for next use. Store the glass upside down to keep dust and salt spray out and keep the cap on the TDS meter.

 

[Icefire]

Get a replacement, You might got a bad one.

 

[cthetoy]

Changing your membrane is alot cheaper than changing your DI. Your DI should last almost 10x longer if your TDS is 10 coming out of RO.