RODI filter problems/improvement

[Galeno rocha]

Hi all! In need of help with my RPDI filtration system.
I own a 100 gdp three stages (polypropilene+carbon+DI Resin) plus RO membrane filter with pressure pump.
My source is about 260 tds.
The problem I have is that I can't get my filtered water below 45ish. It has been like that since day one.
First I replaced the polypropilene and carbon medias. It took over an hour to wash them and still water comes around 4 ppm higher after these two. Than a replaced the DI resin and its container, which was damaged due to me wrongly screwing it in.
Still getting same results.
I'm ordering a new membrane, but not shure if I'm going the right way and don't wanna waste more money.
I notice my polypropilene stage get really dirty and brown right on the first day. Should I get more stages?

 

[Lbrdsoxfan]

You may need another stage, but that's weird.

I consistently test at 0-1 tds with a 4 stage setup running at 75 psi (no boost) and my water at the tap hovers between 250-350 tds.

There are some solid rodi gurus here, hopefully you'll get some help.

 

[LeftyReefer]

It sounds like you actually have a 4 stage RO/DI, not a 3 stage.
#1 sediment
#2 carbon
#3 RO membrane
#4 DI resin

If your particulate filter (stage 1) is getting dirty fast you probably have a lot of particulates in your water so you might want to get a better quality (lower micron) sediment filter to catch the particulate before they clog the rest of your filters.

Make sure your RO membrane is inserted all the way..

Do you have any TDS meters on your system? They really help pinpoint where the issue is.
If you know your incoming source water TDS and what it is after your RO membrane, then you can keep track on how your membrane is working and know when its time to change.

Do you know the micron rating of your filters? sediment and carbon?

with source water TDS of 260, you should be seeing TDS of around 5 - 10 if your RO is working properly.

 

[Kazumi]

The sediment and carbon stages will not lower TDS. They just remove solids. How did you wash them?

 

[Jerrym21]

If possible, mount your di stage vertical. If not, a lot of water will bypass the resin that will lay on the bottom of the cartridge.

 

[LeftyReefer]

The fact that you have always gotten 45'ish TDS out of your system since day one is weird. That's why I suggest checking that your RO membrane is actually inserted all the way. Something isn't right. Either your DI is shot and adding TDS or your RO membrane isn't working correctly. or both. You should not be seeing 45 TDS.