Problem with Custom DI Setup

[redfishbluefish]

This has me absolutely and totally perplexed!!!


I regenerate my DI resin….been doing it for some time. This is not the issue.

The biggest PIA is first separating the two resins to clean them up.


So I was fortunate to come upon an old RO setup with two canisters.

I figured I’d remove the RO membrane and polishing carbon filter and turn it into a DI unit with separate “beds”…….The cationic resin in one, and the anionic resin in the other. This way, when I go to regenerate, no first step of separating the two resins. I purchased two DI canisters from BRS and had plenty of resin to get this thing going.

I will tell you that in the process of taking off the RO stuff, I noticed the two canisters, that are labeled “IN” and “OUT,” had both “OUTs” connected. I flipped this one canister around so that the “OUT” of the first canister entered the “IN” of the second canister.


So here is my problem….I now have attempted this three times….I can’t get down to zero TDS. My most recent attempt was letting the unit run for six hours, and after six hours, I can only match the TDS of the incoming water. The same result for all three separate times I’ve tried this.

(The number on the left is TDS before the DI resin, the number of the right is after the DI resin.)

Now, I take this same resin and mix it up and put in it a single canister and I’m now back to zero TDS within a minute of starting the water flowing.

What’s going on???

 

[jgraz]

Have you tried to reverse the 2 resins. I really have no idea what I'm talking about but figured I'd throw it out there

 

[Mark...]

Could somehow the resins need each other in combo (mixed) to actually work? Some kind of synergy?

 

[kschweer]

Very interesting. Maybe try reaching out to azdesertrat on r2r. He really seems to know his stuff when it comes to rodi.

 

[redfishbluefish]

Have you tried to reverse the 2 resins. I really have no idea what I'm talking about but figured I'd throw it out there

Good point. The first two times I attempted this, I did not take note of the order of the two canisters. In discussing this at a meeting where David (Malulu) was there (he has a Kati/Ani unit....a bigger version of what I'm trying to do), he stated the it was called "Kati/Ani, so Kati comes first. This most recent attempt was with the cationic resin first....no dice.

 

[redfishbluefish]

Could somehow the resins need each other in combo (mixed) to actually work? Some kind of synergy?

I'm a chemist and have used exchange resins multiple times...and have a patent on use of one for radioactive stuff. So I think I know how they work. They are simple "exchange" resins. The bad stuff is attracted to the respective resin and, in the process either kicks out a hydrogen or hydroxy ion. It is "exchanged" for the hydroxy or hydrogen ion. The bad stuff has a greater affinity for the resin. So they do not need each other.

 

[redfishbluefish]

Very interesting. Maybe try reaching out to azdesertrat on r2r. He really seems to know his stuff when it comes to rodi.

Thanks Kevin....it's posted over there as well.

 

[redfishbluefish]

When I was typing the OP, I came to the part about the IN and OUT of the two canisters and thought, “What the hoot, let me flip them back around and see what that does.” I wasn’t overly optimistic, but maybe these RO folks know something I don’t know. By the way, the IN side allows water to enter on the outside of the inner canister, and exit by going up the inner canister….and vice versa.

No dice! I only let it run for five minutes, but the outflow was now greater than the in flow.

 

[kschweer]

I know this is a dumb question but I know I've made dumber mistakes myself. Was the resin you used recharged or just separated waiting to be recharged?

 

[redfishbluefish]

I know this is a dumb question but I know I've made dumber mistakes myself. Was the resin you used recharged or just separated waiting to be recharged?

Kevin, with me, this is a valid question. I've had my Homer "Duh" moments.

The source of resin is separated and recharged. It is the same source I've been using for some time. Each time I've had to change my mixed bed, I've gone and tried the separate bed (using the same resin). When that wouldn't work, I've then remixed resin to a mixed bed to get back to making clean water.

These were about 75-80 percent filled when I started trying to make this work.

 

[Zippy69]

Well Paul on a side note I have like 7 pounds of the stuff for you to recharge and use. I guess I'll drop it when the food comes in.

 

[kschweer]

Did you ever figure this out Paul?

 

[redfishbluefish]

Did you ever figure this out Paul?

NO! '#@!%


I'm looking for a cement wall to bang my head.


I will tell you that I've been toying with this for over a year or so. I set it up quite a while ago and tried it....it didn't work, so I made "mixed bed" and ran that until it needed replacing. I again tried it and it didn't work.....and repeat step one, one more time. So I've now made another mixed bed and probably won't play with this again until that needs to be changed.


I posted it here, on R2R and RC....some responses on R2R, nothing on RC. The R2R comments didn't add up, so I'm still scratching my head. Frustrating.

 

[Empire]

Flow pressure reading?

 

[malulu]

1. may be you TDS meter is bad? tried different one? i assume these things get old too?

2. dirt inside somewhere in the cartridge?

3. what is wrong with the output as 1 ?? it still mean near perfect already...


4. try to give it some meaningful input source (real tap) water... and see if the output is really still as 1.
if it is really 1 or 2... it is a success - don't be too picky...