TDS question

[ricwilli]

I use a Kati Ani for filtering water but have not used it for about two months cause I'm to lazy to regenerate it. But anyway... I've been using my backup RO/DI unit and I forgot to change the DI resin. Now I have a 55 gallon drum full of RO/DI water with a TDS of 019 ppm. I know we all strive for 000 TDS, but man, will it hurt to dump 55 gallons of water down the drain. Is a TDS of 019 that bad that I can not use it as top off water?

 

[Srixon]

I know people who have used worse and those who use tap water will little ill effect

 

[AZDesertRat]

Did you test the DI water straight from the RO/DI output or from the storage container? If its from the unit then thats probably not good, if its from the container it could just be dust or residual salt.

What is the TDS of the RO only water before it gets to the DI?
If the RO is lower than the 19 then that means you are releasing weakly ionized substances from the spent DI resin and it could be all nitrates, phosphates and silicates which are all weakly ionized substances.
If the RO only is about equal to or greater than the 19 then its possible the DI is doing a little bit of work but is near exhaustion and will soon begin sloughing off and releasing everything it has captured over time.
DI must also be stored wet and cool or it loses its electrical charge, if you are not using the RO/DI for an extended period remove the membrane and DI cartridges and stick them in the refrigerator in a zip loc bag with some DI water in it so they stay fresher. Even then DI resin has a shelf life of about 6 months if it has been opened and 1 year if it is still factory vacuum sealed.

 

[goody]

I know some people use water from those water machines outside grocery stores for their top off. I decided to try it and it measured 15ppm on my tds. I didn't notice anything noticeably different, but I think I'm going back to using my RO/DI. What I'm saying is I wouldn't dump that water, I would use it as top off.

 

[ricwilli]

Did you test the DI water straight from the RO/DI output or from the storage container? If its from the unit then thats probably not good, if its from the container it could just be dust or residual salt.

What is the TDS of the RO only water before it gets to the DI?
If the RO is lower than the 19 then that means you are releasing weakly ionized substances from the spent DI resin and it could be all nitrates, phosphates and silicates which are all weakly ionized substances.
If the RO only is about equal to or greater than the 19 then its possible the DI is doing a little bit of work but is near exhaustion and will soon begin sloughing off and releasing everything it has captured over time.
DI must also be stored wet and cool or it loses its electrical charge, if you are not using the RO/DI for an extended period remove the membrane and DI cartridges and stick them in the refrigerator in a zip loc bag with some DI water in it so they stay fresher. Even then DI resin has a shelf life of about 6 months if it has been opened and 1 year if it is still factory vacuum sealed.

Thanks AZ for the explanation. I have not tested the tds from the RO. I will test soon. I learned something new today in that di only has a shelf life of 6 months.

I think I will use the water.