RO SYSTEM TDS QUESTION

[jfbhd4]

I have a RO system that is now reading 10-20 PPM. I had not flushed the system in a few months (forgot), but finally flushed it and still getting high reading.

Which stages do i have to replace to get this back to 0 ppm?

 

[jfbhd4]

 

[Lbrdsoxfan]

Usually sediment, carbon and DI resin

 

[SPR1968]

Id try just changing the DI resin first, that’s all I change most of the time, and just change the other filters every 12 months or so. And I make a huge amount of water

 

[Gtinnel]

Is the tds 10-20ppm after the membrane but before the di or is that after the di? Also what is your source water tds? It sounds to me like you probably need a new membrane and di, but I'd go ahead and replace the pre filters as well.
Replacing just the di should bring it back down but if the water going into the di is up to 20ppm it will be depleted quickly. At a 98% rejection rate, for the water to be coming out of your membrane at 20ppm your source water would have to start at 1000ppm tds which I think would be unlikely. Once the water coming out of my membrane rises to around 4 I replace it (my tap water is 100ppm tds).

 

[Woodyman]

I have a RO system that is now reading 10-20 PPM. I had not flushed the system in a few months (forgot), but finally flushed it and still getting high reading.

Which stages do i have to replace to get this back to 0 ppm?

Are you getting the 10-20 before or after your DI?

If before, then what type of reading did you typically see in the past? Also what is your incoming TDS prior to the membrane?

If after DI, then yes time to change DI, and possibly membrane, just depends on what type of values your seeing.

 

[Woodyman]

Is the tds 10-20ppm after the membrane but before the di or is that after the di? Also what is your source water tds? It sounds to me like you probably need a new membrane and di, but I'd go ahead and replace the pre filters as well.
Replacing just the di should bring it back down but if the water going into the di is up to 20ppm it will be depleted quickly. At a 98% rejection rate, for the water to be coming out of your membrane at 20ppm your source water would have to start at 1000ppm tds which I think would be unlikely. Once the water coming out of my membrane rises to around 4 I replace it (my tap water is 100ppm tds).

Forgot to refresh before I posted! Now where is @KStatefan :p

 

[Adamantium]

Have you tested TDS between your RO Membrane and your DI cartridge?

Get a meter that you can put inline. They're not very expensive, and it will tell you the whole story.

You want a 98-99% or so reduction in TDS right after the membrane, and then the DI essentially "polishes" that and gives you 0 TDS.

The most likely culprit is the DI, and if it's color changing you can easily tell if that's the problem. The reason the meter would help is that while it could be the DI, it could also just be that your RO membrane is letting through way too much TDS, and therefor your DI can't polish it. DI resin is made to deal with water that's like 1PPM up to 20PPM at the absolute most. Any more than that and you'll basically use it all up in 30 minutes, and start getting TDS in your output water.

 

[KStatefan]

Forgot to refresh before I posted! Now where is @KStatefan :p

I think you and @Gtinnel have it covered.