Reversed DI/CARBON on my RODI

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BoxKing

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Brand new 100GPD 4 Stage RODI unit I setup yesterday, and just my luck, I placed the Carbon and DI cartridges in the others respective place. I ran the system for about three hours this way, all while checking with my HANNA TDS Probe- first reading was 16TDS. It was late in the evening so I didn’t see some of the carbon sediment at the bottom of my bucket DUH!! Well, I swapped out the cartridges, and ran the unit for the past 5 hours. Randomly testing the water and I still have 16 TDS. DI cartridge is half yellow/blue. Did I destroy the DI only; is the membrane suspect now as well?

Should I just replace both DI + Membrane?
 
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Yes, by putting the DI in the carbon block spot, you flushed source water TDS through it... exhausting it in short order. You will need a new DI cartridge.

What brand membrane do you have? Also, what is your source water TDS. Knowing this information, we can determine the efficiency of your RO membrane and figure out our options from there.

If it’s a brand new system, the membrane should be fine.
 

ExoS

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A quality membrane like the Dow version BRS sales should be rated for 2000 ppm*hours of chlorine. At potable water levels of chlorine for three hours, no harm was done to the membrane. The di isn’t hurt either beyond whatever was consumed trying to exchange all the tds
 
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I purchased the system from my LFS.. literally stripped of any branding so I can’t tell you which membrane is in it without pulling it apart.

My TDS in is 296. Roughly 2/3 of the DI cartridge is exhausted, so I’m going to assume its burnt out.
Looks like I need to replace the DI, and purchase a new membrane tomorrow just in case. I’ve also replaced the output hose for fresh water just in case its still housing any carbon sediment Internally.
 

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Well I just used the Dow membrane as an example because I knew it’s rating from memory. Cheaper membranes may be more susceptible but the point is that your membrane probably saw less than six ppm*hours of chlorine and is rated for thousands. It’s not hurt. You don’t need to buy a new one
 
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Assuming that you exhausted your DI membrane and have a 296 source water TDS, at 16 TDS post RO, it looks like you’re getting a 94.6% rejection rate from your 100 GPD membrane.

Get a new DI cartridge and you should get down to 0. Though with 16 TDS post RO, you will still be ripping through DI resin fairly quickly.

Now if you replace your generic 100 GPD membrane with a Dow Filmtec 75 GPD membrane at a 98 to 99% rejection rate along with the correct corresponding flow restrictor, you can reduce your post RO membrane TDS down to 3 to 6 TDS. That will go a long way towards preserving your DI resin life.
 
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100% depleted the DI... it was pure gold color when I emptied the canister. Replaced with a fresh bag of DI material, and after 20 mins of flushing, it went down to 1TDS... hopefully after a bucket or two it will reach 0.

Thanks again for confirming what my stupidity caused!
 
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