TDS reading -> membrane filter replacement?

[xeanliao]

Hi, after changing the pre-filters, the TDS reading right before getting in DI is still at 27. I should've read it right before replacing them :-(., but I think it is higher than last year.

Is TDS 27 after membrane acceptable? If not, without other testing kits, would you go after replacing membrane filter next? It was about 4-5 years old. Any suggestions?

 

[C. Eymann]

4-5years old? 27ppm tds output.

Definitely replace them membrane

 

[Greg P]

I'd say yes replace it.
If, for example, your Membrane's rejection rate is 98%, then 27 output would tell us your tapwater is about 1350TDS, which is not likely.

 

[DDenny]

What is your TDS after DI? You stated it was 27 before DI.

 

[xeanliao]

What is your TDS after DI? You stated it was 27 before DI.

 

[xeanliao]

What is your TDS after DI? You stated it was 27 before DI.

I also just changed resins as well.
For line 2 (after cation and antion), it is always higher than line 1, that doesn't make sense so I always ignore line 2 reading.
For line 3 (final after mixed resin), It is zero now. I think it was about 10, but again, I really regretted that I forgot to record it before change the filters, but since it read zero now, I careless and it is the line 1 that concerns me

 

[xeanliao]

I'd say yes replace it.
If, for example, your Membrane's rejection rate is 98%, then 27 output would tell us your tapwater is about 1350TDS, which is not likely.

logical + smart!

 

[Greg P]

To get the most out of your DI you want the Membrane to do all the heavy lifting.
What is your tapwater TDS and PSI?

 

[N3mo]

Definitely replace the membrane and di resin as well.

 

[Greg P]

Plus you want to ensure you're using the correct carbon cartridge whether you have chlorine or chloramines.
I'm assuming you're on city water

 

[xeanliao]

To get the most out of your DI you want the Membrane to do all the heavy lifting.
What is your tapwater TDS and PSI?

yeah, I am with you, that is why I concern about line1 reading. Going to replace it !
My psi is 75. I think it is a little low, but not low enough to install a booster, do you think so? I don't know the tapwater TDS. I only have the TDS meter come with the RODI system.

And yes, I am on city water, do you know which type of carbon cartridge I should use? I did not know it matters until now. Great great question for me to learn the right way.

 

[DDenny]

I use a handheld TDS meter HM 100. City tap is 670, RO before DI 25 after DI 0. I like the handhelds cause you can calibrate them not sure about the inline ones.

 

[Greg P]

yeah, I am with you, that is why I concern about line1 reading. Going to replace it !
My psi is 75. I think it is a little low, but not low enough to install a booster, do you think so? I don't know the tapwater TDS. I only have the TDS meter come with the RODI system.

And yes, I am on city water, do you know which type of carbon cartridge I should use? I did not know it matters until now. Great great question for me to learn the right way.

You should know what your pressure coming into your system is, before your Prefilter. This will help you knowing how efficient your RO membrane is.
You also need to know what the TDS of your tapwater is to calculate how efficient your Membrane is.
Forgive my typos

 

[Greg P]

I asked previously what your Tapwater TDS and PSI are
You stated PSI 75
That is great
Check your Tap TDS

 

[xeanliao]

I have a second membrane, BRS 150 GPD Water Saver Upgrade Kit. installed 3 years ago.

I will have 2 new membrane today, thinking:
Do you think the 1st membrane may get exhausted more than 2nd one (or perhaps the other way around?), if yes, would you shift the 2nd one to be the first one and replace the older membrane with new membrane for now? Or, would you just replace both at the same time given the output is not good already?

 

[Screwgunner]

They are 50 gallon per day so if you use 2 you get 100 gallon per day they work together at the same time so they will deplete at the same speed .should be good for a couple years.

 

[KStatefan]

I have a second membrane, BRS 150 GPD Water Saver Upgrade Kit. installed 3 years ago.

I will have 2 new membrane today, thinking:
Do you think the 1st membrane may get exhausted more than 2nd one (or perhaps the other way around?), if yes, would you shift the 2nd one to be the first one and replace the older membrane with new membrane for now? Or, would you just replace both at the same time given the output is not good already?

The second membrane will see higher tds water then the first but i would change at the same time.