DI Resin - exhausted in 2 days?

[redfishbluefish]

You have an RO tank? This is not recommended for RO/DI because of the break-through TDS that ends up in the tank. If you keep it this way, you will go through DI much quicker. Tee off after the membrane (assuming you are using the tank water for drinking) and run that tubing to your DI. If you're not using the tank for drinking water, simply eliminate the tank.

 

[AZDesertRat]

Borrow a handheld TDS meter and take your tap TDS, RO only TDS and final RO/DI TDS.
A RO membrane will never ever produce 0 TDS, they are a 90-98% efficient device so it is impossible. There will always be some TDS in RO only water. The inline lacks the accuracy, especially on the low end to catch this.
If your final RO/DI TDS is actually higher than your RO only TDS that tells you your DI resin is exhausted and is releasing weakly ionized substances back into the treated water.

 

[Shep]

Borrow a handheld TDS meter and take your tap TDS, RO only TDS and final RO/DI TDS.
A RO membrane will never ever produce 0 TDS, they are a 90-98% efficient device so it is impossible. There will always be some TDS in RO only water. The inline lacks the accuracy, especially on the low end to catch this.
If your final RO/DI TDS is actually higher than your RO only TDS that tells you your DI resin is exhausted and is releasing weakly ionized substances back into the treated water.

Can you recommend a good tds meter?

 

[AZDesertRat]

HM Digital TDS-3, TDS-4TM or AP-1 are all good ATC compensated meters in the $25-$30 range. Their COM-100 is the best, most accurate meter around, can test down to tenths and is around $55-$60. I have owned all of the above and currently use the COM-100 with the AP-1 as my backup. Loved the TDS-4TM too.

 

[Browner20]

So I switched around the units and replaced all the filters including the RO membrane this weekend. I did not change out the DI resin because it is still blue but I did order some new resin and replacement foam pads. I am still getting a reading of 3ppm out of the membrane and 2 from the DI chambers. I only did two really brief tests after I changed the filter media so I will give it a couple days to make sure there is not just some residual TDS from the change out.