Can't get my RODI to go below 1.2 TDS in Palm Beach County (SE Florida)

[sickman]

I am losing my mind. Bought 2 additional TDS meters of increasing quality, still can't believe I can't get below 1 TDS.

I bought a typical RO system, 6 stages for my drinking water last year. 90gal/day RO membrane. Replaced all carts last month.

Then I added a canister with catalytic carbon (chloramine blaster) as my 2nd stage since we notoriously have high chloramines here in Palm Beach county.

Then after the membrane I T'd off to two DI resin canisters.

The water coming out of the RO membrane is 4 TDS.

The water coming out of the two DI resins after only hits 1.2 - 1.5 TDS. The cheapo handheld and inline TDS meters show 1 or 0, and the more sensitive higher resolution HM Digital HMDCOM100 is consistently just above 1 TDS at 1.3 - 1.5.

I let the system run 30 minutes before testing the water.

This is the order of the filters for RODI water when I make tank water:

1. Sediment
2. Catalytic Carbon (chloramine blaster)
3 GAC
4. CTO
5. Pressure pump
6. RO membrane
7. DI mixed bed di resin
8. DI mixed bed di resin


Where do I go from here? AI is telling me all sorts of crap like maybe my water has high CO2, and all sorts of nonsense.

 

[wvned]

I think the best move is to do an ICP test that includes a sample of your RODI water.
That would hopefully tell you what is left in the water causing the reading. It may be something you don't really have to worry about.
You should look and see if someone has done an in depth analysis of the contents of your tap water and posted it somewhere online.
The two I see mentioned for your area are chlorate and iron. Those should come out with your filter set up though.

 

[griss]

This is a strange one. Your TDS out of the membrane is actually pretty good at 4, IMO. Mine is typically 6-7 out of the membrane. Then, I have Cation, Anion and Mixed Bed to arrive at zero TDS. I think @wvned has a good suggestion above.

The only other thing I can think of is, you maybe got a bad batch of DI resin.

 

[sickman]

yep, logically has to be that the resin is bad, or poorly packed, ordered new batch and will pack it myself this time. No way after two DI chambers it shouldn't be "0".