Used RO/DI reading 0 TDS. Any need to change?

[BurlyWizard]

Hi all,

I purchased a used 4-stage RO/DI system with a 2 input TDS meter. When initially turning on the system, the TDS's jump up to about 10 or 11, but after a few minute "purge", both the In and Out readings slowly drop to 0 TDS, where they stay as long as you're still pumping water.

Is there any reason/need to change any of the filters/carbon/components? I don't know how long the previous owner had been using them.

What risk could be introduced to the system if I don't change it and the water is registering at 0 TDS?

Thanks!

 

[PeterB113]

Hi all,

I purchased a used 4-stage RO/DI system with a 2 input TDS meter. When initially turning on the system, the TDS's jump up to about 10 or 11, but after a few minute "purge", both the In and Out readings slowly drop to 0 TDS, where they stay as long as you're still pumping water.

Is there any reason/need to change any of the filters/carbon/components? I don't know how long the previous owner had been using them.

What risk could be introduced to the system if I don't change it and the water is registering at 0 TDS?

Thanks!

0 tds is what your looking for but i would test for ammonia and ph just to be sure.

 

[Doostur]

You need to look at your city water report. See what they are using to clean your water. For example if they use 300 Chloramines and your membrane has a 98% rejection rate, then your TDS after the membrane should be 6ish. That is you reference point. If you have a pressure gauge, also make note of that for reference. As those numbers change it may indicate your membrane needs replaced.

When I turn mine on, I'm at 170 TDS. I flush it for 5-10 minutes and it comes down to about 10. When i close off the membrane, it comes down to about 3-5.

 

[AJsReef]

I would replace the sediment filter (super cheap no reason not to) and carbon blocks to ensure chlorine/chloramines aren’t hitting the membrane stage.

Then keep rough track of gallons produced and replace carbon based on manufacturer recommendations for chlorine/chloramine or establish a cadence based of usage over time; every six months, etc.

 

[mdb_talon]

I would change your prefilters. They are cheap, dont last long, and protect your more expensive RO membrane. Even with bad prefilters you can get 0... but it prematurely wears out your RO and DI.

 

[Sleepydoc]

0 tds is what your looking for but i would test for ammonia and ph just to be sure.

pH is generally not very accurate with DI water because there are so few dissolved solids and ions.