Rodi (mostly di) help!

[reefercorey]

I got a used 5 stage rodi and when i intially got the plumbing figured out i was getting an output tds of 70ish. I bought a new membrane and new media and still got about 70. I figured something weird was good on so i tested tds right after the membrane and its only about 5-6ppm. So my question is what could be going wrong after the member. Either the di or carbon block are adding almost 65ppms. Any ideas why this is happening? I've seen people say it could be bad di resin but i doubt that the last resin and this brand new resin were both bad.

 

[phg1960]

I see no reason to run a carbon block as the last stage. Remove the carbon block and retest. You should be putting out 0 TDS after the DI.

 

[reefercorey]

I removed the carbon block and the water doesnt make it to the output tube, it just dribbles out of the spot where the carbon came from. Im not sure if theres a way to plug that spot or something

 

[phg1960]

So you are saying that with the carbon block in, you get water out that reads about 70ppm. But with the carbon block out, you get no flow. I'm misunderstanding something that you're saying.

Can you post a pic of the system again?

The flow should go like the below diagram. I assume that yours has and extra canister, containing the carbon block, after the DI.

 

[reefercorey]

No, no. Sorry for the confusion. I get water out but when I remove the last canister the water just comes out from where that canister was and not from the output tube. Wait... I think I just figured it out, so I remove the carbon from the last canister but leave that canister attached to the system. Ahhh it all makes sense now. Hopefully I can get to 0 when I try it tomorrow though I was so excited to see 005 today.

 

[phg1960]

Yup, No need to remove the canister, just the carbon block that sits inside of the last stage. Once you do that let about a gallon flow through then recheck you TDS.

 

[reefercorey]

Well removed the last carbon and got 005. Much better than the 70 with the carbon but just about the same as the water straight out of the membrane. Well 5 is good enough for me. Thanks for all your help and patience phg1960!

 

[phg1960]

You're welcome.

Seems like your DI is not doing it's job though. Try running a few gallons through the system and see if the output drops lower. If it doesn't, I'd remove the DI cartridge and check to make sure the gasket is present. It's just a rubber flat washer that sits on top of the canister. The one in the photo below is black. Yours may be a different color. If the gasket is missing, the water will bypass the DI resin. That would explain why the DI stage is not lowering the TDS. Replacements are easy to come by. I probably have one in my parts box that I could mail to you.

Stock photo. Your resin is probably not the same color or showing as two layers.

 

[gwdemos]

Water pressure? Waste ratio? Not sure what you have but be sure to get the pressure accurate to your membrane and tweak the waste ratio as well.


Sent from my iPhone using Tapatalk

 

[reefercorey]

Phg1960, I think you are some kind of psychic. I checked my di and it just didn't look right. Looked in the bag of extra stuff that I got from the original owner and sure enough there was the rubber gasket. Going to give it a try now. Fingers crossed for 000