RODI tds 2ppm

anthony1017 · Apr 6, 2022

Ok so I just changed all the filters including my membrane on my 5 stage rodi.

and I’ve let the water run well over 3 hours, And my built in tds meter if giving me a 2ppm reading.
What could be going on? Before I was getting a 0ppm before I started to get 4ppm and then replaced the filters.

Fatmike92 · Apr 6, 2022

anthony1017 said:
Ok so I just changed all the filters including my membrane on my 5 stage rodi.

and I’ve let the water run well over 3 hours, And my built in tds meter if giving me a 2ppm reading.
What could be going on? Before I was getting a 0ppm before I started to get 4ppm and then replaced the filters.

Personally I would be too worried.

I have well water and my RODI runs 2-3 ppm

I usually don’t look into switching things out until around 10-15 ppm

BrandonS · Apr 6, 2022

did you replace the DI resin?

Would also check all the O rings. Sometime the o ring on the membranes or filter cartridge can get squished and allows water to bypass.

Miami Reef · Apr 6, 2022

anthony1017 said:
Ok so I just changed all the filters including my membrane on my 5 stage rodi.

and I’ve let the water run well over 3 hours, And my built in tds meter if giving me a 2ppm reading.
What could be going on? Before I was getting a 0ppm before I started to get 4ppm and then replaced the filters.

Is the DI resin packed well? It needs to be packed extremely tight.

anthony1017 · Apr 14, 2022

Miami Reef said:
Is the DI resin packed well? It needs to be packed extremely tight.

Yes I’ve even replaced all the filters again including the membrane. Now I’m getting 1tds with flush valve closed. But I get 0 tds with flush valve open. Idk what I’m doing wrong

jmichaelh7 · Apr 14, 2022

You need 0 or prepare for issues

Miami Reef · Apr 14, 2022

anthony1017 said:
Yes I’ve even replaced all the filters again including the membrane. Now I’m getting 1tds with flush valve closed. But I get 0 tds with flush valve open. Idk what I’m doing wrong

Try packing the DI resin even harder. It should be very very tight. You should struggle to screw the lid back on with all the pressure. Yes, that tight.

PigFarmer · Apr 14, 2022

jmichaelh7 said:
You need 0 or prepare for issues

Not even close to truth

EeyoreIsMySpiritAnimal · Apr 14, 2022

What is the TDS out of the tap? Are you able to also measure it after the membrane but before the resin? (I disconnect the tubing to get a sample)

EeyoreIsMySpiritAnimal · Apr 14, 2022

anthony1017 said:
Yes I’ve even replaced all the filters again including the membrane. Now I’m getting 1tds with flush valve closed. But I get 0 tds with flush valve open. Idk what I’m doing wrong

I know you said you ran the system for a few hours, but how long did you flush it?
I know when I replaced all my filters there were instructions to run the unit with JUST the sed and carbon for x minutes, then add the membrane and run it for an additional period before putting the DI inline.

Miami Reef · Apr 14, 2022

Erin1971Texas said:
I know you said you ran the system for a few hours, but how long did you flush it?
I know when I replaced all my filters there were instructions to run the unit with JUST the sed and carbon for x minutes, then add the membrane and run it for an additional period before putting the DI inline.

I understand where you are coming from, but I really think this isn’t the issue. 1TDS tells me there’s a problem with the DI resin.

EeyoreIsMySpiritAnimal · Apr 14, 2022

Miami Reef said:
I understand where you are coming from, but I really think this isn’t the issue. 1TDS tells me there’s a problem with the DI resin.

Agree, but thought I'd share my recent experience too. Others already posted about the resin

And getting a reading before the resin would be a good idea regardless

Randy Holmes-Farley · Apr 14, 2022

The concern with 2 ppm tds coming out of a DI is that some compounds may be increased in concentration relative to the incoming water. Ammonia, for example, may be far higher as stronger binding ions Pop it off the DI where it may have accumulated. That mostly relates to when a DI depletes, however, and not so much to a new but imperfectly functioning DI.

anthony1017 · Apr 17, 2022

Ok im about to just give up, Ive done pretty much everything i can. I even bought a brand new ROdi system and a brand new TDS reader. And the new system is showing 4ppm after, i followed the instructions and i have a higher tds reading on the new system now.

I also got a manual tds reader and it showing 3-4ppm with the new and old RODI units. Im using the same city water as before i used to get 0ppm until i changed my filters and now i cant get it down to 0ppm.

anthony1017 · Apr 17, 2022

Ok im about to just give up, Ive done pretty much everything i can. I even bought a brand new ROdi system and a brand new TDS reader. And the new system is showing 4ppm after, i followed the instructions and i have a higher tds reading on the new system now.

I also got a manual tds reader and it showing 3-4ppm with the new and old RODI units. Im using the same city water as before i used to get 0ppm until i changed my filters and now i cant get it down to 0ppm.

gbroadbridge · Apr 17, 2022

anthony1017 said:
Ok im about to just give up, Ive done pretty much everything i can. I even bought a brand new ROdi system and a brand new TDS reader. And the new system is showing 4ppm after, i followed the instructions and i have a higher tds reading on the new system now.

I also got a manual tds reader and it showing 3-4ppm with the new and old RODI units. Im using the same city water as before i used to get 0ppm until i changed my filters and now i cant get it down to 0ppm.

Measure the incoming water TDS, the TDS following the membrane going into the DI resin and post them.

What temperature is the water going into the RODI filter and do you know the source?

If the RODI unit has incoming water pressure meter, what is that psi?

edit: Also measure how many cups of waste water are generated for each cup of DI water coming out.

anthony1017 · Apr 17, 2022

gbroadbridge said:
Measure the incoming water TDS, the TDS following the membrane going into the DI resin and post them.

What temperature is the water going into the RODI filter and do you know the source?

If the RODI unit has incoming water pressure meter, what is that psi?

edit: Also measure how many cups of waste water are generated for each cup of DI water coming out.

Ok so incoming tds is reading at 193ppm and before going into the DI tds is reading 2ppm. Manual tds is reading 5ppm.
Tempasure is 25c and i believe its city water. Water pressure is 60psi with out the boster pump and 100psi with boster pump.

gbroadbridge · Apr 17, 2022

anthony1017 said:
Ok so incoming tds is reading at 193ppm and before going into the DI tds is reading 2ppm. Manual tds is reading 5ppm.
Tempasure is 25c and i believe its city water. Water pressure is 60psi with out the boster pump and 100psi with boster pump.

Ok that tells me that the membrane is doing its job just fine and it's great that you're running a booster pump.

The DI resin is not working. Are you sure it is mixed resin (both anion and cation)?

You said that you replaced the entire filter, so are you sure that the resin cartridge is seated correctly and that water is not bypassing the resin?