Rodi

[Hilltopreef90]

I bought a brand new 5 stage rodi system and it was reading 9 on the tds meter, it’s been a year and a couple filter and resin changes and I’m still reading between 2-4 tds.
I don’t understand why ‍ my previous system was always at zero unless it was close to needing a resin change.
I’m going to try changing the membrane and filter once more and hope it drops to zero.
Regardless is it safe enough to use the water in my aquarium with it measuring 4 on the tds meter?

 

[Indymann99]

I bought a brand new 5 stage rodi system and it was reading 9 on the tds meter, it’s been a year and a couple filter and resin changes and I’m still reading between 2-4 tds.
I don’t understand why ‍ my previous system was always at zero unless it was close to needing a resin change.
I’m going to try changing the membrane and filter once more and hope it drops to zero.
Regardless is it safe enough to use the water in my aquarium with it measuring 4 on the tds meter?

Are you reading the TDS after membrane (4 would be reasonable) or reading TDS after resin (final output and should be 0)?

 

[twentyleagues]

Do you know what your tds is out of the tap? Typically you get a 90ish% tds drop out of the membrane and the rest is handled by resin. I have seen crazy high source tds and still have a reading of some level of tds at the filtered water.

 

[Hilltopreef90]

Do you know what your tds is out of the tap? Typically you get a 90ish% tds drop out of the membrane and the rest is handled by resin. I have seen crazy high source tds and still have a reading of some level of tds at the filtered water.

Around 34 out of the tap

 

[twentyleagues]

Around 34 out of the tap

oh wow yeah they should probably be 0 then. I am sorry if I missed it where is the test being taken?

 

[Hilltopreef90]

I have a tds meter on my system and I bought another tds meter to check my tap water
I’m not sure what you mean as far as where the test is being taken. Im in north Florida

 

[twentyleagues]

At what point in your rodi is the tds meter? before the resin or after?

 

[Hilltopreef90]

After the resin

 

[twentyleagues]

After the resin

do you have a pressure gauge? if so whats the pressure?

 

[Troylee]

Might need booster pump… if you’re not pushing around the 80psi range the membrane isn’t working to its full potential… 34tds is crazy good outta a tap! My tap in Vegas is 572 “face palm” out of my membrane 6-8 and the resin handles the rest but gets depleted quickly… good ole city water ugh.

 

[vetteguy53081]

Either a pressure issue or high TDS prior to entering unit. Also assure cartridges are not upside down creating back pressure

 

[Buckeye Hydro]

I bought a brand new 5 stage rodi system and it was reading 9 on the tds meter, it’s been a year and a couple filter and resin changes and I’m still reading between 2-4 tds.
I don’t understand why ‍ my previous system was always at zero unless it was close to needing a resin change.
I’m going to try changing the membrane and filter once more and hope it drops to zero.
Regardless is it safe enough to use the water in my aquarium with it measuring 4 on the tds meter?

Good posts in this thread.

To recap:
Tap water TDS: 34 ppm
RO water TDS: unknown
DI water TDS: 4 ppm

Water pressure at the membrane: unknown

So Hilltop - would you get those numbers for us?

Is your DI resin cartridge installed with the big black rubber washer on the top or on the bottom?

Another question: Are you using a TDS meter with inline probes, or are you using a handheld TDS meter? If inline, are the probes rotated correctly in the tees?

When you look at your DI cartridge, do you see any empty space inside the cartridge? Look near the top of the cartridge.

Do you see any color change in the DI resin? If so, is the color change near the top, or the bottom of the cartridge?

Russ