TDS 1 but drops to 0 over time while in bin?

[Madison Reef]

So I have a mystery I cannot explain with RODI (BRS unit).
My source water is less than or around 300 TDS, and the RO membrane (99% rejection rated dow) takes it down to around 6-8 before going into DI resin.
After DI resin it comes down to 1 TDS.
The process ate up DI resin fast compared to source water (TDS ~180) I had before, I did some online search and I heard my city has CO2.
So today I was about to degas, and run it through with new DI resin, but I just found out that TDS dropped to 0 while in bin with closed lid.

I did not oxygenate it, it was in two separate brute bins with closed bin for about a week.
Could you please explain what happened here and if I should run the water (currently TDS reading 0) through new DI resin?

Thanks!

 

[Fish Think Pink]

So I have a mystery I cannot explain with RODI (BRS unit).
My source water is less than or around 300 TDS, and the RO membrane (99% rejection rated dow) takes it down to around 6-8 before going into DI resin.
After DI resin it comes down to 1 TDS.
The process ate up DI resin fast compared to source water (TDS ~180) I had before, I did some online search and I heard my city has CO2.
So today I was about to degas, and run it through with new DI resin, but I just found out that TDS dropped to 0 while in bin with closed lid.

I did not oxygenate it, it was in two separate brute bins with closed bin for about a week.
Could you please explain what happened here and if I should run the water (currently TDS reading 0) through new DI resin?

Thanks!

I don't change my filters until I'm more like 3-5 TDS (total disolved solids)

Would expect solids settled to bottom, since no mention of circulation in bin.

My vote = Don't kill yourself chasing just 1 TDS.

 

[Madison Reef]

I don't change my filters until I'm more like 3-5 TDS (total disolved solids)

Would expect solids settled to bottom, since no mention of circulation in bin.

My vote = Don't kill yourself chasing just 1 TDS.

Thanks for the explanation.

 

[Rmckoy]

Typically the other way around.

With mine as it sits it naturally attracts anything possible

 

[Randy Holmes-Farley]

I don't change my filters until I'm more like 3-5 TDS (total disolved solids)

Would expect solids settled to bottom, since no mention of circulation in bin.

My vote = Don't kill yourself chasing just 1 TDS.

Dissolved ions don’t settle from solution.

 

[Randy Holmes-Farley]

Typically the other way around.

With mine as it sits it naturally attracts anything possible

Which includes CO2 from the air, which raises tds.

 

[Randy Holmes-Farley]

Thanks for the explanation.

It’s not correct.

 

[Randy Holmes-Farley]

So I have a mystery I cannot explain with RODI (BRS unit).
My source water is less than or around 300 TDS, and the RO membrane (99% rejection rated dow) takes it down to around 6-8 before going into DI resin.
After DI resin it comes down to 1 TDS.
The process ate up DI resin fast compared to source water (TDS ~180) I had before, I did some online search and I heard my city has CO2.
So today I was about to degas, and run it through with new DI resin, but I just found out that TDS dropped to 0 while in bin with closed lid.

I did not oxygenate it, it was in two separate brute bins with closed bin for about a week.
Could you please explain what happened here and if I should run the water (currently TDS reading 0) through new DI resin?

Thanks!

Id ignore it. It might be test error, or some sort of chemical reaction. Nothing bad happens to di water as it sits that would lower tds.

 

[Madison Reef]

Typically the other way around.

With mine as it sits it naturally attracts anything possible

Dissolved ions don’t settle from solution.

That was my understanding.

Which includes CO2 from the air, which raises tds.

Is it possible that since my source water has CO2, suppose gas exchange happened thus lowered TDS from 1 to 0?

Thanks!

 

[Julbra]

What is the resolution of your TDS meter? If it’s 1 then a possible explanation is that your water is around 0.5 TDS and you just have some rounding to the nearest TDS happening in the meter. This is more likely as the temperature compensation kicks in, for example if the water has warmed up or cooled down while sitting in the bin.

 

[Randy Holmes-Farley]

That was my understanding.

Is it possible that since my source water has CO2, suppose gas exchange happened thus lowered TDS from 1 to 0?

Thanks!

Possible, but unlikely. CO2 is removed by a di, and CO2 will increase in di water.

Most likely it is a testing issue and I’d just ignore it.

 

[Madison Reef]

What is the resolution of your TDS meter? If it’s 1 then a possible explanation is that your water is around 0.5 TDS and you just have some rounding to the nearest TDS happening in the meter. This is more likely as the temperature compensation kicks in, for example if the water has warmed up or cooled down while sitting in the bin.

I am not sure about the resolution, but it does not have decimal point. It only gives me a whole number.
After reading your comment about temperature, it makes much more sense. I took TDS measurement at two different temperature (cold when RODI is produced vs warm when it sat at the basement for a while).
Thank you so much.

Possible, but unlikely. CO2 is removed by a di, and CO2 will increase in di water.

Most likely it is a testing issue and I’d just ignore it.

Thank you for advice. I will just ignore it.