Rodi tds question

[xmjxflipx]

Good evening, i have a RODI question. I have a air water ice extreme typhoon with a senna dual online tds meter. I back flush for 10 mins and let it run for 10 mins. Main issue per se.is I see 1 tds on the out after di. The resin is color changing so it's not exhausted, weird thing is I tested with a handheld tds and it shows 0. Anyone can think of why dual online is different from the handheld?
Also wanted to add the only time I saw the online showing 0 tds if I unhook the di cartridge and pour out the water and let the system fill back the canister, it will show 0 tds. When the system bleeds out the air trapped in the canister and it's not full of water it goes back to 1 tds. Is the di canister suppose to be half full of water or filled with water all the way to the top?

 

[theMeat]

All the way to top

 

[Sean Clark]

A few possibilities:
1 your water supply uses chloramines, you need to use dual carbon blocks for this
2 you are experiencing ammonia breakthrough, you need to use dual carbon blocks or additional di stages
3 you're di is expelling ammonia prior to displaying exhaustion due to a cation/anion imbalance in your source water.

 

[DrinkinPepsi]

Your DI needs to be packed tight, Make sure your TDS sensors are positioned where the water flows through the prongs. What is your TDS going in and coming out of RO? I assume your DI resin is mixed bed?