7 Stage RODI not producing 0ppm

[anizato]

Hey all,

I have a 10 year old BRS DELUXE 6 stage RODI system. I added a second membrane for saving water a few years ago.
Recently, I moved to a house with amazing water pressure and got 2xmembranes 100GPD. so now I have 200GPD.

My TDS incoming from the city is 38. the water coming out of the DI Resin is 6 at the lowest. I have a HM D-2 Dual TDS Meter that came with the original purchase. It has never been recalibrated, but I don't think it needs to be?

The DI resin was packed by myself, so maybe that could be it? there is a lot of air in the DI Resin cartridges. about half. So I am not sure, some people say that shouldn't affect the results of the TDS.

I also tried this with a single membrane just to discard that possilibity that my flow isn;t what I believe. But alas, there is indeed wonderful water pressure here, so that is not a factor. I still couldn't get less than 8-6ppm TDS.

Everything is new but the cartridges themeselves.

1 x 1 Micron - 2.5" x 10" Sediment Filter - Neo-Pure

2 x BRS Universal Carbon Block Filter - 1 Micron

2 x One Cartridge Refill (1.25 lbs.) DI Resin

2 x 100GPD membranes

1 x 800ml flow restrictor/flush valve

 

[saltytanked]

Ya you’re doing something wrong! And two membranes is just a waste and doesn’t improve anything. Point of diminishing returns.

 

[KrisReef]

I’m lost, but to troubleshoot these things you have to measure the output from each stage, ro, then di (from both membranes) to see if the output is greater than the input. Misalignment of membranes or orings can cause issues, and membranes can fail. When the filter is working properly the TDS should be lowered between each stage of filtration.

The di can be spent and loose packing of di allows that stage to fail at removing the last TDS, if it is spent or too loosely packed.

Gl

 

[Formulator]

Double check the TDS meter accuracy with some store bought distilled water.

 

[anizato]

at one point I had the tds meter read the same line and they both read the same. i placed them on the very end of the product line after the di resin, and it was 7ppm. So TDS meter working!
Then I placed one tds reader at the beginning of the DI resin and it read 8ppm.... so for some reason the DI Resin doesn't seem to be working.

I definitely did not pack it too lightly, so maybe i packed it too tightly? There is a significant amount of air in the DI resin cartridges, not the containers, the container holds the resin tight, and the container goes inside the cartrdige which you later twist onto the rest of the filter (just to clarify). Should I remove the DI Resin and repack it with less resin?

so the water comes in at 38, I removed the second membrane and it brings it down to 11ppm - 8ppm. then the resin brings it down to 6ppm - 4ppm.

What does this tell you ?

 

[Formulator]

at one point I had the tds meter read the same line and they both read the same. i placed them on the very end of the product line after the di resin, and it was 7ppm. So TDS meter working!
Then I placed one tds reader at the beginning of the DI resin and it read 8ppm.... so for some reason the DI Resin doesn't seem to be working.

I definitely did not pack it too lightly, so maybe i packed it too tightly? There is a significant amount of air in the DI resin cartridges, not the containers, the container holds the resin tight, and the container goes inside the cartrdige which you later twist onto the rest of the filter (just to clarify). Should I remove the DI Resin and repack it with less resin?

so the water comes in at 38, I removed the second membrane and it brings it down to 11ppm - 8ppm. then the resin brings it down to 6ppm - 4ppm.

What does this tell you ?

What kind of resin are you using? Maybe not a single stage resin. Could be cationic or anionic instead of a mixture you need for a single stage DI canister.

 

[anizato]

city water ppm

 

[anizato]

Double check the TDS meter accuracy with some store bought distilled water.

the thing is the tds meter is an inline meter so it only reads water flowing through it. I was thinking of getting a pen though and see what that says. You can always return stuff on amazon, right?

What kind of resin are you using? Maybe not a single stage resin. Could be cationic or anionic instead of a mixture you need for a single stage DI canister.

I am using the mixed resin from BRS

 

[Formulator]

I am using the mixed resin from BRS

Hmmm. I find it very hard to believe that the TDS is the same before and after the resin. Even poorly packed, the resin is going to absorb something unless the water is somehow completely bypassing the resin.

 

[disaster999]

Ya you’re doing something wrong! And two membranes is just a waste and doesn’t improve anything. Point of diminishing returns.

Lots of misinformation here.
2 membrane is not a "waste". Hooked up in series where the waste water from one RO membrane goes in the inlet of the second membrane can increase the production of RO water without doubling the amount of waste water thus is saves water instead. With the TDS of his tap water being this low to begin with, the OP will see little to no accelerated depletion of his RO membrane.

 

[anizato]

Hmmm. I find it very hard to believe that the TDS is the same before and after the resin. Even poorly packed, the resin is going to absorb something unless the water is somehow completely bypassing the resin.

so then I could have completely overpacked the resin then? is that a possibility? I do see the resin getting wet though, but as I mentioned before there is a lot of air in those DI containers

 

[Formulator]

so then I could have completely overpacked the resin then? is that a possibility? I do see the resin getting wet though, but as I mentioned before there is a lot of air in those DI containers

Maybe. Is the air in the space between the resin and outer container? That doesn’t make much sense to me in a properly set up filter can. Do you have it all assembled tightly and correctly and the water in/out lines aren’t swapped by mistake? How long did you try to run it before stopping and assuming something was wrong? Might just need to prime and let it run for 10-15 minutes if you didn’t already do that.

 

[disaster999]

Did you JUST packed the resin yourself, ran the system and noticed the high TDS? If so, let the system run with the freshly packed DI resin for a few gals. Its probably just flushing what ever junk on the resin at first, you SHOULD start to notice it drop and eventually go back to zero.

Ive seen some new resin have high TDS initially, but settles down back to zero when everything is flushed.

Edit: I also noticed after your carbon filters you have a T where it splits the water. One goes somewhere not shown and the other enters your RO membranes. Im guessing you are filtering the water for something?

 

[Opus]

Make sure you installed your DI cartridge correctly. The arrow on the cartridge should point up. I had mine installed upside down and the tds was the same in and out on new DI media.

One observation. You are not getting good numbers from your RO membranes. At 40 going in you should be getting 1 coming out, maybe 2 at worst. My tds is 450 at the tap and it is 5 after the RO membrane.

 

[KrisReef]

@Opus is correct about the rejection rate of your RO filters. They are supposed to remove 90% of the TDS, at least, many of them remove 95-9888888888888888888888888888888888888888888888888888888888888888888888888889 (key stuck, just gonna leave that there) so starting with 40 you should have a most 4 TDS coming out, and many filter membranes would get it down to 2 or 1 TDS in the first pass.

Loose DI resin allows the water to channel inside the canister and can prevent water from flowing through all of the media so that much of it doesn't get used at all as the water goes through the path of least resistance. Along that path the resin becomes exhausted, and the results are no good.

I think the filter may not be properly assembled a with the two RO membranes? The resin that was used to recharge may have been too old? Resin has a shelf life and can fail over time before it goes in the canister. It is a charged bead that can lose its ability to attract ions from out of the water.

 

[anizato]

all is new, new sediment filter, new carbon blocks, new di resin, new 100GPD membranes.
basically everything except for the canisters

I tried a few configurations with the TDS meter, I figured out that both probes work at least they both give out the same reading when connected to the same line.

I also removed on membrane and tried to see if that would remove the last of the 6or7ppm TDS. but it did not.

So I then put the TDS meter before and after the DI Resin... it suprised me to see that from 8ppm it only went down to 7ppm...
I did notice, at a point when I removed the DI Resin to shake up the containers, when the water was filling up again, there was a lot of air in the DI canisters. if you flip the DI unt (aka the 2 canisters

Then on to the DI Resin.... unpacked and repacked it. I added a flow restrictor to the end of the product line, because I wanted to create pressure inside the DI Resin canisters and remove all air... so i was successful in doing so and saw the water creep up the resin cartridges. So That air factor has been removed.

I did notice this however, when applying pressure to the DI Resin. See if this says anything to anyone. When the pressure was on in the di resin canisters, the TDS out read 5ppm... when i released it, while the pressure was at max, it would spit down to 2ppm.
BUT... at the same time I would hear air bubbles inside one of the membranes.

I moved the TDS meters around and found out both probes work, if they are misscalibrated they are misscalibrated exactly the same, since they both read the same ppm from the same line.
So that is discarded also. Until I can get my hands on a different TDS meter.

I tried running the system without the membrane that was making the air bubble sound and still 5 to 8 ppm. I can't figure out what is happening here. I have wasted so much water I feel beyond guilty. When initially all I wanted was to SAVE water....

so not only have I wasted water and enough money that I could have purchased a new entire rodi system... so frustrating. Now I have to drive to the LFS and BUY RODI water... this is insane!

The T that diverts the water from the DI to the black line for a drinking container. We drink the water produced before the water hits the DI resin.

 

[DED65]

Did you rinse your pre filters for awhile before running it through the RO membrane?

 

[anizato]

Make sure you installed your DI cartridge correctly. The arrow on the cartridge should point up. I had mine installed upside down and the tds was the same in and out on new DI media.

One observation. You are not getting good numbers from your RO membranes. At 40 going in you should be getting 1 coming out, maybe 2 at worst. My tds is 450 at the tap and it is 5 after the RO membrane.

I freaking love you man! you figured it out! after all the troubleshooting and wasted time and water... all it was were the friggin di cartridges upside down!

Thank you to the entire coummunity who tried to help! I tried everything and all suggestions given to me. We ALL did it together as a reefing community. Pretty awesome to be a part of!

Thanks again to everyone!

Happy Friday and Happy Reefing!

 

[Opus]

@Opus is correct about the rejection rate of your RO filters. They are supposed to remove 90% of the TDS, at least, many of them remove 95-9888888888888888888888888888888888888888888888888888888888888888888888888889 (key stuck, just gonna leave that there) so starting with 40 you should have a most 4 TDS coming out, and many filter membranes would get it down to 2 or 1 TDS in the first pass.

Loose DI resin allows the water to channel inside the canister and can prevent water from flowing through all of the media so that much of it doesn't get used at all as the water goes through the path of least resistance. Along that path the resin becomes exhausted, and the results are no good.

I think the filter may not be properly assembled a with the two RO membranes? The resin that was used to recharge may have been too old? Resin has a shelf life and can fail over time before it goes in the canister. It is a charged bead that can lose its ability to attract ions from out of the water.

Any idea on the shelf life of DI media? I had some that was probably 4 or 5 years old and dried out. I still used it and got 0 tds with it. It seemed to last as long as using brand new DI media.

 

[KrisReef]

Any idea on the shelf life of DI media? I had some that was probably 4 or 5 years old and dried out. I still used it and got 0 tds with it. It seemed to last as long as using brand new DI media.

I do not. Supposedly if it is store properly it is ok.