Di output not getting to zero even with new cartridge

[joe-ejs]

Hello.

I have an issue with my RO/DI. Input coming out of the RO membrane to the DI is about 16. The output from the DI fluctuates around 9. I just replaced the DI and gave the same results. Any suggestions what the issue might be?
Any advice would be much appreciated

thanks

 

[Familyman2010]

Hello.

I have an issue with my RO/DI. Input coming out of the RO membrane to the DI is about 16. The output from the DI fluctuates around 9. I just replaced the DI and gave the same results. Any suggestions what the issue might be?
Any advice would be much appreciated

thanks

How long have you had the unit? May be time to replace tds sensor.

 

[Phil D.]

Add a second DI cartridge

 

[joe-ejs]

How long have you had the unit? May be time to replace tds sensor.

I do have a 2nd tds meter which is a HM digital and it reads similar to the tds meter on the RO unit. So that rules out the meter. Is it possible something bad is getting through the membrane which the DI cannot process?

 

[Trey]

What unit do you have? How many Stages? Which prefilters and carbon blocks? mixed bed DI? Anion? Cation?

I have relatively low TDS water from the tap and I run two units, both 7 stage, 3 membranes, 3 prefilters, 3 carbon blocks, anion, cation, and 3 di mixed beds....

Could the solution be more stages for you?

 

[ca1ore]

Check to make sure the DI resin is well packed in the plastic cartridge. It might be channeling. Also make sure the black gasket is on the top of the cartridge. Otherwise water will be bypassing the resin.

 

[joe-ejs]

So this is a new di canister pre-filled. It seems like the water is bypassing it. RO output to the di is about 11 and output of DI is around 5 or 6. I also had a strange issue when I replaced the last DI. I had to run about 100 gallons through it before it dropped to zero. When it was exhausted last week, the top half of the DI canister was exhausted color - brown, but the bottom half was still black. Opposite of what should happen. So it seems that water was bypassing the DI for a period of time or something else is happening.

any advice or suggestions would be much appreciated as I can’t make top off water right now at zero TDS