TDS is higher out of DI resin then the membrane

[ReeferBee]

Than*

The TDS coming out of my RO membrane is 1 while the TDS from my DI resin is 3. Any ideas? My only guess is that some resin is coming out through the effluent somehow. I use BRS color changing DI resin, and it's a little orange, but not fully exhausted by any means.

 

[Frop]

Than*

The TDS coming out of my RO membrane is 1 while the TDS from my DI resin is 3. Any ideas? My only guess is that some resin is coming out through the effluent somehow. I use BRS color changing DI resin, and it's a little orange, but not fully exhausted by any means.

My first thought is if the TDS meter is working right. not sure if they malfunction if the batteries were low or anything or if the tip was bent idk. Just curious.

 

[Tony Elenbaas]

Have you tried swapping sensors?

 

[ReeferBee]

Have you tried swapping sensors?

Yep, same reading on different sensors.

I also let the rodi run for 30 minutes to see if it would change.

 

[ReeferBee]

Could be low battery, the screen flickers but to get the same reading with the sensors swapped is odd

 

[Tony Elenbaas]

I would replace the DI resin, I run 2 canisters. You can see the resin change colour and I replace them both before the colour change reaches the top of the last one.

 

[Buckeye Hydro]

Sounds like your resin is bad.

Russ

 

[Randy Holmes-Farley]

While it might just be poor accuracy in measurement, it isn't impossible for the conductivity to rise in passing through a spent, or partly spent DI resin.

You sure its a mixed bed and not just a cation or anion resin? Using either of those alone will also boost the conductivity as larger ions are replaced by either H+ or OH-, both of which are very conductive.

 

[fity2pounder]

Any outcome to this? I’m having this happen to me too. I run two cation cartridges, followed by four anion cartridges, followed by one mixed bed cartridge. Only the very first anion cartridge is about half depleted based on color changing. I had the same thought that maybe some of the di resin was coming through if I didn’t pack the cartridge tight enough but wasn’t sure if this wld increase tds or not. Does having too many cartridge cause problems? Do cartridges have to be replaced after a certain time period regardless of being depleted (my actions have been there for many months as my city water basically only needs anion according to color changes over the last year or two). Any other ideas or recommendations? Thanks!!

 

[Buckeye Hydro]

"Packing the cartridge tightly" is an issue primarily for up flow mixed bed cartridges. You pack them tightly because you don't want the anion beads to separate from the cation beads - you want then to stay mixed.