How to Read TDS Meter?

Dinkins Aquatic Gardens · Oct 21, 2021

I have a 7-stage BRS RODI system, but I'm confused on what the built-in TDS meter is saying. It has a selector with three settings - line 1, line 2, and line 3. I'm assuming line 1 is the source water, perhaps line 2 is the water coming out of the RO, and line 3 is fully deionized RODI product water. But my "line 1" shows 1-2 ppm, while line 2 and line 3 show 0. Not that I'm complaining, but surely there's no way my city water has a TDS of 1-2 ppm, is there? No city tap water is that clean?

Am I reading it wrong/confused about what I'm reading?

KStatefan · Oct 21, 2021

ddink7 said:
I have a 7-stage BRS RODI system, but I'm confused on what the built-in TDS meter is saying. It has a selector with three settings - line 1, line 2, and line 3. I'm assuming line 1 is the source water, perhaps line 2 is the water coming out of the RO, and line 3 is fully deionized RODI product water. But my "line 1" shows 1-2 ppm, while line 2 and line 3 show 0. Not that I'm complaining, but surely there's no way my city water has a TDS of 1-2 ppm, is there? No city tap water is that clean?

Am I reading it wrong/confused about what I'm reading?

Where are the sensors placed?
Does the system have a three stage DI? If so I would assume first one is after membrane, second is before mixed bed and third is final product water.

hhaase · Oct 21, 2021

All depends on where the individual probes are located. Going by their online description it's measuring before the DI system, after the single bed resins, and after the mixed resin. So that means it's likely measuring AFTER the sediment filter, carbon blocks, and RO membrane. Thus not measuring your incoming tap water.

-Hans

Fredinva · Nov 16, 2021

If you put a probe on your inbound water, now you know. Whether its 100, 200, 400, it's not going to change much in the future. Thus, the probe could be moved somewhere to give you a better idea what you system is doing. My two probes are after membrane and after dual resin canisters. Good enough for me.