Ro/di tds readings

[Cory]

After my deionization resin the tds reads 000. But after a carbon filter it reads 023. Why is this?

 

[Marty.h]

Mine are as follows

Tap water just under 300

After membrane anywhere between 3-8

After Di 0


I don't measure inbetween pre filters and membrane

 

[Cory]

I see. But the carbon filter is for taste and drinking purposes and is at the end of the unit, after the deionization resis. It appears its releasing soemthing effecting tds. I know carbon is conductive, perhaps its completing the circuit? Or is this perhaps phosphorus from the manufacturer perhaps not acid washing the carbon. Thoughts? The carbon is a culligan gac disposable tube.

 

[Marty.h]

My system runs in this order


Water in

Pre filter wadding

Carbon canister

Booster pump plumbed in here switched on when needed.

Membrane

Di resin

Out to storage

 

[Randy Holmes-Farley Verified Community Expert]

I see. But the carbon filter is for taste and drinking purposes and is at the end of the unit, after the deionization resis. It appears its releasing soemthing effecting tds. I know carbon is conductive, perhaps its completing the circuit? Or is this perhaps phosphorus from the manufacturer perhaps not acid washing the carbon. Thoughts? The carbon is a culligan gac disposable tube.

Is this an RO/DI, or DI only?

The carbon filter should be before the RO membrane to protect it from chlorine and chloramine.

Maybe you have one in both places?
There should be little to nothing left after the DI for a carbon filter to remove if the DI is post an RO membrane.

 

[Cory]

This is an ro/di. It goes through sediment filter first, then a carbon filter, then to the reverse osmosis membrane, then the dionization resin, then a final carbon filter at the end. However after the carbon filter at the end the tds raises to 023 from 000. Strange?

 

[D maul]

If your using it for drinking water run a splitter to avoid the carbon filter at the end for the fish.

 

[Randy Holmes-Farley Verified Community Expert]

This is an ro/di. It goes through sediment filter first, then a carbon filter, then to the reverse osmosis membrane, then the dionization resin, then a final carbon filter at the end. However after the carbon filter at the end the tds raises to 023 from 000. Strange?

I doubt it is hurting anything, but I also doubt it is a useful add on filter.

The idea is presumably to bind the few compounds that make it through the DI, but it seems unnecessary.

 

[Cory]

Ah ok. The carbon at the end was my addition for drinking the water. But one day the water tasted horrible despite reading 000, so i added the carbon at the end just in case. It had a sour taste.

 

[AZDesertRat]

Plumb your RO/DI following this diagram so you use RO only via the post RO taste and odor GAC carbon filter for drinking water and keep the DI for reef use. It is easy to do and only involves installing a 1/4" tee and 1/4" inline check valve.
The TDS you are seeing after the GAC filter is normal. It is partially due to the soft carbon eroding to dust as water flows through it. You don't want nor need a post carbon for DI, only for the RO only drinking water.
http://spectrapure.com/huds/4-STAGE-DWK-RODI-NAG.pdf

Do not drink the RO/DI, only the RO. DI tastes very bland or blah and is not refreshing since it has been stripped of everything while RO still has some mineral content so tastes much better, especially after passing through the carbon to remove the rubbery taste common with RO.

 

[Cory]

Thanks AZdessert rat. Thats quite an awesome image. And ill plumb the ro/di that way. I figured it was normal, but thanks for the confirmation.