RODI issues

[evil Nick]

My buddy has an RODI unit. He was having trouble with output and the first step was changing the cartridges out which seemed like it helped with the flow. We then purchased a TDS meter and it was reading VERY high. like equal to tap.
Well it turned out the guy he bought it from had it hooked up wrong.

he had
solids, carbon, THEN membrane off to the resin.

I corrected it to
solids, carbon, resin THEN membrane last.

We tested some initial output and it was actually HIGHER than the tap water lol. I figured this was because there was garbage in what was the new output since they were swapped around to be correct.
We decided to run some flush buckets and after one 5 gallon (im not there right now) he got 200 from tap (which is what I got) and 160 from RODI. Not very good.
Hes going to flush 10 gallons. I asked him to check the microns on the other filters.
They also sent us a TFM 18 membrane instead of a 24. We read the only difference was the daily output.

Can anyone tell me what else we could look at here? waste water is also reading equal to tap

 

[Sniperhank]

You are sure all of the filters and resin simply don't need replaced at this point?

 

[evil Nick]

You are sure all of the filters and resin simply don't need replaced at this point?

no we replaced them all, sorry thought I specified that, my bad.

 

[Sniperhank]

Membrane old?

EDIT: Also, the resin should come after the membrane. If you look at most units, you will see them go through the typical filters like carbon then into the membrane. Then water flows into the 'separate' unit that houses either one or a pair of resins.

 

[evil Nick]

Membrane old?

EDIT: Also, the resin should come after the membrane. If you look at most units, you will see them go through the typical filters like carbon then into the membrane. Then water flows into the 'separate' unit that houses either one or a pair of resins.

yup I just saw that at my LFS. I went last night to inspect theirs and saw it actually was hooked up right. I have to swap it back around. The membrane is also new.
We cant understand why wehen going through all 4 stages our TDS is still reading the same as tap. Big problem is we each already used a bucket of the water!!!!

 

[coralbandit]

What is the pressure on the system and what brand is this unit....
The unit should produce water with a TDS that is less then 10% of source in worst case scenario..Pressure often has a great impact on performance after source water...

 

[evil Nick]

What is the pressure on the system and what brand is this unit....
The unit should produce water with a TDS that is less then 10% of source in worst case scenario..Pressure often has a great impact on performance after source water...

to be quite honest Im not sure of the pressure. Thanks for reminding me. I have my pressure guage in the car and meant to check it there but it was missing its washer so I waited.
I know the membrane says 18gpd @ 65psi. I figured less psi just meant less water, will that actually affect the quality as well?

 

[evil Nick]

Figured it out. His PSI was around 80, which is correct for our area. I actually installed a pressure reducer on our main because of this.
Anyway I went to the LFS who has basically the same setup and realized it was actually set up wrong.
it was right where the DI resin is last, but the last guy setting it up was using the second out on the membrane as the finish water. So the membranes two outs were the waste and finish. I cant remember how he hooked it up so the DI was originally last but it was wrong. This is probably good though because I had the DI cartridge in upside down. Dont drink and DI folks. Either or its up and running great now. Making 0 tds water like a champ.
We did notice though that the resin went from blue to copper in just like 7 - 5gallon pails of water. Not sure if thats normal.

 

[coralbandit]

DI is the quickest exhausted of the canisters...
Use both the color and a meter to know when to change it.

 

[Sniperhank]

Glad things worked out.

 

[evil Nick]

Thanks guys. One thing I also just read was most people flush the new sediment and carbon cartridges out before inserting the resin and DI ones. We def didnt do that. Live and learn.

 

[Sniperhank]

Yes, the new carbon cartridges normally need flushed due to the dust that comes off of carbon.