Can't ge to TDS

[cnote2991]

I need help figuring out why I cannot reduce my RO to 0 TDS. I get 2 TDS before DI and 2 TDS after DI.

It is new resin in dual canisters. I thought the seals on top of the cartridges might be bad allowing the water to bypass the resin, so I replaced with new canisters. The membrane and carbon blocks are kinda old but seem to still be functioning.


Here's what I have so far:

157 ppm source
2 ppm after membrane
2ppm after dual di
50-55 psi @ membrane

All checked with handheld HM TDS/TEMP calibrated with 342 ppm solution.

Any suggestions?

 

[Jgomez324]

Do you run any water thru the new resin before testing?

 

[TheEngineer]

How well packed is the resin?

 

[cnote2991]

Resin is packed tight. Feels solid if I squeeze it. Basically can't get any more in there.

 

[cnote2991]

Ran water through for about 20 minutes before testing.

 

[Jgomez324]

You might want to run a few more gallons out.

 

[cnote2991]

Will do. I did make up 75 gallons through this resin before I switched the canisters. Maybe it needs run a while with the new canisters.

What happens here? Does the resin settle out or something? I don't see how it could seeing how tightly it is packed.

How long do people usually run before getting good water after changing resin?

 

[AZDesertRat]

Resin should rinse up in one or two bed volumes so maybe 1 gallon with two DI's.
What brand and blend of resin are you using, how old is it, how was it packaged when shipped, where did you get it, how have you stored it and how did you pack it? Resin has a fairly short shelf life even when packaged properly and stored properly.
What model TDS meter are you using? Is it a ATC compensated meter such as the TDS-3, TDS-4TM or AP-1? What is your water temperature and the room temperature where you are testing the TDS?
What are you testing in and how? Is it a squeaky clean clear glass drinking water glass washed by hand in extremely hot water so it does not have any dishwasher soap or anti water spotting films on it? Do you draw the water directly from the filter in question directly into the glass? Do you triple rinse the glass with distilled or RO/DI water between each individual test?

 

[cnote2991]

BRS color changing resin. Brand New. Vacuum sealed in mylar bad of individual 10" canister portions. Did not store it. Put it straight intp use. Packed as normal... filling 1\3 and tamping down...2/3 and tamping down etc. Canisters are full and solid. Cant squeeze them.

HM TDS-3 handheld, which I believe is ATC compensated. Water temp is 73.5F according to tds meter. (actually 23C and I converted) Room temp is 72F. Water drawn into glass that was triple rinsed along with meter using water from each stage of testing.