RO/DI system issues - please help

[g8rorchid]

Hi all,

I've been in the hobby for over 15 years and I have NEVER had this issue. I feel like I have done a ton of troubleshooting and have wasted countless hours on this. I have a countertop/portable RO/DI unit (uses inline filters) and I changed all of my filters and RO membrane. The water is going WAY too fast through the system. There is nothing coming out of the waste water line and the water coming out of the filtered water line has the same TDS as the faucet water. I have tried 2 different RO membranes, changed out the capillary flow restrictor, and nothing has fixed the issue. I let it run for 30-45 minutes to see if for some reason it needed that much time to get the right pressure to make the waste water. I'm at my wit's end. I know the lines aren't mixed up because they came with little tags, so I can't mess that up. Any help would be greatly appreciated!!

 

[Dread Pirate Dave]

Hi all,

I've been in the hobby for over 15 years and I have NEVER had this issue. I feel like I have done a ton of troubleshooting and have wasted countless hours on this. I have a countertop/portable RO/DI unit (uses inline filters) and I changed all of my filters and RO membrane. The water is going WAY too fast through the system. There is nothing coming out of the waste water line and the water coming out of the filtered water line has the same TDS as the faucet water. I have tried 2 different RO membranes, changed out the capillary flow restrictor, and nothing has fixed the issue. I let it run for 30-45 minutes to see if for some reason it needed that much time to get the right pressure to make the waste water. I'm at my wit's end. I know the lines aren't mixed up because they came with little tags, so I can't mess that up. Any help would be greatly appreciated!!

Since this has occurred after changing filters and membrane is it possible something isn't seated correctly or missing an o-ring or seal which allowing the water to bypass it?

 

[Reef.]

My guess is either you haven’t unwrapped the membrane or there is an issue with it, or the flow restritor is either incorrectly fitted or the wrong size.

 

[g8rorchid]

Thanks for the replies! I figured it out - I'm an idiot, lol. I switched the waste water and pure water outlets on the RO housing. I didn't know that they couldn't be switched. This was my first time doing that.
Here's another question though - Once it was running correctly I checked TDS and it kept going up (didn't attach DI yet) - went from 25 to 60 to 70. I swapped out the new RO membrane with the old one and was getting readings of 10. Is the new membrane faulty??

 

[Dread Pirate Dave]

Thanks for the replies! I figured it out - I'm an idiot, lol. I switched the waste water and pure water outlets on the RO housing. I didn't know that they couldn't be switched. This was my first time doing that.
Here's another question though - Once it was running correctly I checked TDS and it kept going up (didn't attach DI yet) - went from 25 to 60 to 70. I swapped out the new RO membrane with the old one and was getting readings of 10. Is the new membrane faulty??

Possibly needs to be backflushed. How long did you run it after fixing the issue? Could be a time thing too.

 

[g8rorchid]

I let it run for 20-30 minutes. I don't know what backflushing is, lol.

 

[Reef.]

Possibly needs to be backflushed. How long did you run it after fixing the issue? Could be a time thing too.

If it’s going up you are probably testing your waste water, as your waste has higher tds than your tap.

 

[Reef.]

I let it run for 20-30 minutes. I don't know what backflushing is, lol.

Some units have a bypass, the tds when the unit is not being run corrects before and after your membrane, sone units have a flush to run this tds out before it gets to your di resin so not to use up the resin faster.