TDS question....

[DJ Monty]

Wasn't sure where to put this so Figured I would try here..
Has anyone had any problems using Brut trash cans for R/O water.. I just found this out on mine...
TDS out of RO/DI unit =0
TDS out of Brut can after at least 24hrs =451
TDS out of faucet = 190
The can was bought new & has never had anything else in it. Been using it for 12 months...

All this = me not happy.. Time to reconfigure my mixing station...

 

[Crabs McJones]

Wasn't sure where to put this so Figured I would try here..
Has anyone had any problems using Brut trash cans for R/O water.. I just found this out on mine...
TDS out of RO/DI unit =0
TDS out of Brut can after at least 24hrs =451
TDS out of faucet = 190
The can was bought new & has never had anything else in it. Been using it for 12 months...

All this = me not happy.. Time to reconfigure my mixing station...

Is the TDS in the brute trash can after 24 hours still RO/DI water or mixed saltwater?

 

[DJ Monty]

It's still RO/DI.. I drop it from the Brut can into my salt mixer... Salt never comes into contact with it...

 

[ndrwater]

Okay... Gonna have to look into this.. I use a Brut too, and have for years...

Just as a thought, I know Brut also makes "food grade" cans as well...

 

[chipmunkofdoom2]

I use a Brute can for RO/DI storage, as do many others. I'm not aware of any other reports like this.

Have you made any changes to the RO/DI system lately? Is it possible you swapped the waste water lines and the Brute is filling with waste water? It's possible for some containers to release chemicals into RO/DI water, but 451 ppm TDS seems high to me. Especially if you keep the Brute clean and nothing has fallen into it.

 

[DJ Monty]

I use a Brute can for RO/DI storage, as do many others. I'm not aware of any other reports like this.

Have you made any changes to the RO/DI system lately? Is it possible you swapped the waste water lines and the Brute is filling with waste water? It's possible for some containers to release chemicals into RO/DI water, but 451 ppm TDS seems high to me. Especially if you keep the Brute clean and nothing has fallen into it.

I haven't made any changes & the can looks clean & always has a lid on it..

 

[Randy Holmes-Farley]

Wasn't sure where to put this so Figured I would try here..
Has anyone had any problems using Brut trash cans for R/O water.. I just found this out on mine...
TDS out of RO/DI unit =0
TDS out of Brut can after at least 24hrs =451
TDS out of faucet = 190
The can was bought new & has never had anything else in it. Been using it for 12 months...

All this = me not happy.. Time to reconfigure my mixing station...

I would not assume it is the can, if you cleaned it.

Some salt spray/dust getting into it will boost TDS, and, moreover, TDS is not itself a problem.

 

[Gordon42]

Do you heat the water in the can?

 

[DSC reef]

This is great info. I never thought about testing TDS after it's been stored. I use a hard plastic 65 gallon trash can on wheels. I can only test what comes from the RODI with the online meter, need to look into a portable meter.

 

[Gordon42]

I monitor the tds going into the can also which reads 0 but since I heat the water in the can the tds for some reason increases. The company that treats my well water told me that a tds reading is always higher in warmer/hot water.

 

[Gordon42]

If you heat the water in the storage that may raise the tds. The company I use for water treatment for my well explained to me that the tds level is always worse in warmer/hot water.

 

[Randy Holmes-Farley]

I monitor the tds going into the can also which reads 0 but since I heat the water in the can the tds for some reason increases. The company that treats my well water told me that a tds reading is always higher in warmer/hot water.

Well, that depends on how you measure it, and the effect is small in this context.

Conductivity is temperature dependent and good meters always automatically make a correction to 25 deg C. Cheap inline meters likely do not, and so yes, TDS rises slightly as temp rises because the ions in the water conduct slightly. But the effect is not great. A doubling of the conductivity/TDS (say, 0.1 to 0.2 ppm TDS, or 5 to 10 ppm TDS) would take a temperature rise of 50 deg C. The actual coefficient is about 2% per deg C.

Temperature Compensation Algorithms for Conductivity
https://www.analyticexpert.com/2011/03/temperature-compensation-algorithms-for-conductivity/

" For dilute solutions of most salts the linear temperature coefficient is about 2% per °C. "

 

[DJ Monty]

Do you heat the water in the can?

I don't need to heat the water in the can.. I live in Central Florida, the water in the can averages around 80 degrees.....

 

[Forsaken77]

If you heat the water in the storage that may raise the tds. The company I use for water treatment for my well explained to me that the tds level is always worse in warmer/hot water.

The tds from the tap is severely higher because it adds sediment from your hot watet heater into it.

I heat my stored RODI water at 80 degrees in a grey Brute can for 2 years and the tds is 0.35with the COM-100 handheld meter.

Brute has cans that are food grade and not food grade. You have to look at the markings on the bottom. It used to be that only the grey cans were food grade, though I think they changed it recently so all cans are food grade. Not positive, but I know for a fact the blue can was not food grade, but someone recently said theirs was. So if it's an older can, it may not be food grade.

 

[Randy Holmes-Farley]

The tds from the tap is severely higher because it adds sediment from your hot watet heater into it.

I heat my stored RODI water at 80 degrees in a grey Brute can for 2 years and the tds is 0.35with the COM-100 handheld meter.

Brute has cans that are food grade and not food grade. You have to look at the markings on the bottom. It used to be that only the grey cans were food grade, though I think they changed it recently so all cans are food grade. Not positive, but I know for a fact the blue can was not food grade, but someone recently said theirs was. So if it's an older can, it may not be food grade.

Sediment alone as a solid material doesn't impact TDS measurements, unless it dissolves.

 

[Forsaken77]

Sediment alone as a solid material doesn't impact TDS measurements, unless it dissolves.

All I know is I have my rodi unit hooked up to both hot and cold using a Y- hose and if I try to make it 77 degrees, you can literally watch the tds climb by a hundred as soon as the warm water is introduced on the tap side.

Randy, from BRS told me this. He also said that warmer water, with the higher tds, will more easily pass through the membrane, using DI resin more quickly. So it's better to just use cold water even though the rejection rate will be lower.

 

[Randy Holmes-Farley]

All I know is I have my rodi unit hooked up to both hot and cold using a Y- hose and if I try to make it 77 degrees, you can literally watch the tds climb by a hundred as soon as the warm water is introduced on the tap side.

Randy, from BRS told me this. He also said that warmer water, with the higher tds, will more easily pass through the membrane, using DI resin more quickly. So it's better to just use cold water even though the rejection rate will be lower.

All of those things may be true (although I'm a bit skeptical of the DI part), BUT the interpretation may not be entirely correct.

If the meter is not temperature compensated, it will read higher in TDS in warmer water even if it has exactly the same material dissolved in it. Each individual ion conducts more at higher temp so it seems like there are more of them. A normal handheld meter should correct for this difference, but cheap inline meters may not.

Solid material (such as gets caught in a sediment filter or collected in a hot water heater) does not contribute to TDS.