another TDS question?

[lms]

ok so I just picked up a RO/DI unit. it was used and seams to work great but I am new to this. I was told you want your tds to be zero, but I am getting a reading of 3 do I need to run the unit longer? or is that ok?
thanks
lis

 

[Joel A]

does it have a DI cartridge as well?

It's normal for water to come out of the RO process with a little bit of TDS (like 3), but then the DI stage after that takes care of the rest of the TDS and gives you your reading of 0.

 

[Sokretys]

3 is still quite low. Zero is def ideal...am i understanding you right that it is being run through DI resin? My setup has a reading of 3 going into the DI and zero after...ive heard a few cases of it not being as zero after the DI. I was under the impression that the DI removed EVERYTHING...it was just a matter of how fast the resin would go bad.

Perhaps it has to do with the psi? i wasnt getting great results as first with my 150gpd. i called filter guys and i guess because it has 2 separate 75 gpd ro membranes it needs 65+ psi...maybe look at ur psi?

 

[lms]

The reading is after the DI. Maybe I just need to replace the DI?

 

[Joel A]

how old is the DI, and is it a color changing resin?

DI certainly does not remove EVERYTHING that it comes in contact with, but it does a great job of cleaning up what the RO membrane leaves behind.

 

[JayM]

The reading is after the DI. Maybe I just need to replace the DI?

what's the reading BEFORE the DI? If it's high, you need to replace everything.

if it's low...maybe just the DI.

I'd also do a visual inspection of the filters before the RO membrane...if they are discolored, it is time for them to go as well.

 

[lms]

I am not sure the age of the DI. as I bought the unit used. I don't think it is color changing.
Can I use the water with a 3ppm tds reading? Is is going to be bad for making salt water or for toping off my 55 gal? And is it go to cause any problems?

 

[Blueflu1]

In my opinion 3 should be ok. I would look to replace the DI soon though cause It will prob continue to climb. I haven an inline TDS meter on my RO/DI unit which measures input and output. My input is around 75 and my output is zero. So if your getting 3 and your input is anything like mine, it is still removing alot of stuff.