Millipore milli-q elix ro system h2o quality report question

[makisupapolice14]

I've been using ro water from the millipore system at my work since last May when I began all grain brewing and building up water profiles. Our service contract for the elix system we have expired quite awhile back and I'm beginning to think, based on recent pH estimates being a bit off, that the quality of the ro water has decreased.

I looked at the elix water quality report on the digital display of the system and received the following values:
Tap feed C: 124 us/cm
Ro feed C: 124 us/cm TC
Permeate C: 20.0 us/cm TC

Ro feed temp is 22.7c at 1psi.

I recall reading TDS for a properly functioning ro system should be <25. Any idea what permeate conductivity measures? Are conductivity and TDS essentially the same? Thanks in advance for the help.

 

[ajdelange]

No, TDS and conductivity aren't the same but they are related. TDS is the concentration of a salt that has the same conductivity as the mix of salts in the solution being measured. The 25 uS/cm could correspond to one value of TDS if the reference is NaCl and another if it is K2SO4. Thus TDS is really only useful, other than for relative measurements, in an industry where, for example, one always measured brine.

We can see from your conductivity numbers that the system is only rejecting to the extent of about 6:1. We'd like to see at least 10:1 and preferably 20:1 or better.

 

[makisupapolice14]

Thanks aj. That's probably why the system is noting that the ro cartridge ionic strength is below the set point. Too bad we dropped the service contract with millipore and no longer maintain the system. Sucks working in govt. looks like I may need to look elsewhere for true ro water

 

[Buckeye_Hydro]

Make sure you run the system for at least a couple of minutes before you look at the conductivity of the permeate.

Your RO Feed Temp seems to indicate the system was off (1 psi) when you looked at the readings.

Russ

 

[makisupapolice14]

You are correct I'll check it later on and report back thanks

 

[makisupapolice14]

Make sure you run the system for at least a couple of minutes before you look at the conductivity of the permeate.

Your RO Feed Temp seems to indicate the system was off (1 psi) when you looked at the readings.

Russ

Here are the values I recorded after letting the system run for several mins:
Tap feed C: 123 us/cm
Ro feed C: 149us/cm TC
Ro feed temp: 29.9c
Ro pressure: 61 psi
Permeate C: 26.2 us/cm TC
Ro rejection: 82.3%
Elix res: 2.1M(omega)cm TC

 

[Buckeye_Hydro]

Does this RO water feed a pressurized tank? Or does it go to an atmospheric tank?

 

[ajdelange]

Looks as if the system has a DI stage as well. I'm assuming that's what the 'Elix resistivity' is. It should be 18 M&#937;-cm

 

[makisupapolice14]

Does this RO water feed a pressurized tank? Or does it go to an atmospheric tank?

I believe it is atmospheric but I'm not sure. Here is a pic of the entire setup

 

[makisupapolice14]

https://imgur.com/a/L2fmM

 

[Buckeye_Hydro]

I'm not seeing any pic at that link