20th Century RO cartrigde??!!

[schwaggs]

I have a 35 GPD Kent Maxima HI S RO cartridge that has been in service since January of 1999, 11 years!!! I have been making at least 50 gallons a week between top-off and water changes. I just replaced the pre-filters (1 micron filter and .5 micron carbon) and the DI cartridges and measured the TDS with an uncalibrated Hanna TDS meter and have these results:

Tap Water - 44 ppm
Output of pre-filters - 34 ppm
Output of RO - 1 ppm
Output of DI - 0 ppm

Does this seem right? Are there other impurities that are making it past this cartridge that are not detectible by the TDS meter that would require replacing the cartridge?

 

[jmaneyapanda]

Im not sure I understand. You've changed everything but the membrane? I would expect TDS to be zero after that.

 

[schwaggs]

Yes but the membrane is 11 years old. Does that seem reasonable? Are there other impurities that an 11 year old membrane is passing that does not show up in TDS?

 

[jmaneyapanda]

I wouldnt think so. I would calibrate the TDS meter, if youre really worried, but a properly maintained membrane can last a while (although 11 years DOES seem excessive). Once the membrane gets to teh end of its useable life, you would see two things- either decreased output, or increase in TDS.

 

[jonathan]

Quite possible. Membranes can last many years if the prefilters are properly maintained.

 

[jmaneyapanda]

Jonathan;444869 wrote: Quite possible. Membranes can last many years if the prefilters are properly maintained.

Agreed. A cheap and quick thing I added to maintain my filter was a Kent flush kit. It costs a minimal amount, and supposedly prolongs the memberane life significantly (in theory).

 

[schwaggs]

I haven't done anything special with mine. I can't even say I replace the pre-filters all that regularly.... I was running it in fairly dirty water for the first 4 years but as you can see, the water here is pretty clean to start with. I'm sure it isn't putting out 35 GPD, maybe 25 at fairly strong tap pressures here. I guess I will keep running it until it slows down too far or TDS rises.

 

[schwaggs]

I just measured its output and it is significantly reduced. It is actually a 60GPD membrane but it is only producing around 28 GPD. I have fairly good water pressure here so the reduced output must have to do with its age... Still more than functional for me, I guess I will see how many more years I can get out of it...

This membrane runs about $114 so it definitely isn't cheap... but it only cost me about $10 a year. :yay: All I can say is Kent HI S membranes are well worth the extra $$$ in my experience.

 

[jmaneyapanda]

Schwaggs;447969 wrote: I just measured its output and it is significantly reduced. It is actually a 60GPD membrane but it is only producing around 28 GPD. I have fairly good water pressure here so the reduced output must have to do with its age... Still more than functional for me, I guess I will see how many more years I can get out of it...

This membrane runs about $114 so it definitely isn't cheap... but it only cost me about $10 a year. :yay: All I can say is Kent HI S membranes are well worth the extra $$$ in my experience.

If you dont have it already, get the flush kit. Its a tiny expense, and (in theory) should assist in "cleaning" the membrane.