Which of my ISP RO results should be of concern?

Rst

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Please advise. Here are my recent RO water results. Which ones should be of concern and should be lowered or closer to 0ppm:
I added a new carbon cartridge just before this test.

P 0.02ppm (Phosphorus)
Rb. 0.02ppm (Rubidium)
Ca 0.42ppm (Calcium)
Mg 3.58ppm (Magnesium)
K 0.62ppm (Potassium)
Na 17.12ppm (Sodium)
Cl 11.22ppm (Chlorine)
S 2.91ppm (Sulfur)
Sr 0.02ppm (Strontium)
I 0.01ppm (Iodine)
B 0.01ppm (Boron)

NOTE: All other elements were at 0ppm
 

clifg

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Chlorine would be the most dangerous I would think. Are you using a 3 stage? Might be time to upgrade to a 5 stage with two carbon and two DI filters. For reference, mine came back with all 0's.
 
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Chlorine would be the most dangerous I would think. Are you using a 3 stage? Might be time to upgrade to a 5 stage with two carbon and two DI filters. For reference, mine came back with all 0's
Sorry. see next post
 
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Wow, I was afraid that (most?) reefers get all zero results. My RO system did also have a fresh container of DI as well and my end result TDS was zero as needed although my TDS after my double membranes was 2.

My RO membranes were replace almost 2 years ago and so far I have made approximately 7500 gals of RO water. If it is time to replace these 2 membranes, these cost about $500 for the pair.(designed to produce 1000 gal/day). Maybe I get poor results because my RO water goes too fast through the membranes?

Is it time to look for a better quality but smaller production RODI system?

Any advise would be greatly appreciated.
 

Randy Holmes-Farley

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There are two possibilities.

Either these results are inaccurate, or the water is not even close to 0 ppm TDS. The actual value is above 30 ppm TDS.
 

Randy Holmes-Farley

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FWIW, there's no reason to assume there is any chlorine present. Chloride is by far the most abundant anion in seawater and in most freshwater, and would be present in tap water in substantial amounts.
 
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FWIW, there's no reason to assume there is any chlorine present. Chloride is by far the most abundant anion in seawater and in most freshwater, and would be present in tap water in substantial amounts.
Randy, really appreciate you chiming in here.

Randy, do I understand your advise correctly? According to my ICP results if correct, my inline 2 TDS meters should show much higher than zero?

There might be some other mitigating factors at play here:
1. My rodi system is currently missing the usual mechanical first cartridges. Tap water goes directly to the carbon cartridge.
2. My tap water temp is 45 deg F. (Winter here now)
3. My water supply pressure is low (45psi)
4. This rodi system is designed to produce(move) massive quantities of water(rated at 1000gal/day) thru quickly, hence sacrificing quality results? My RO needs are far below needing huge amounts quickly, currently using no more than 40 gals of RO water every 2 weeks.

Sadly, I don’t know where to go from here. Determining where the existing problems are and fixing them seems daunting.

Starting over with a new quality rodi system might be my best option. I really want to achieve the all zero
ppm quality results mentioned above.

Thanks for your feedback.
 

Randy Holmes-Farley

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Randy, really appreciate you chiming in here.

Randy, do I understand your advise correctly? According to my ICP results if correct, my inline 2 TDS meters should show much higher than zero?

There might be some other mitigating factors at play here:
1. My rodi system is currently missing the usual mechanical first cartridges. Tap water goes directly to the carbon cartridge.
2. My tap water temp is 45 deg F. (Winter here now)
3. My water supply pressure is low (45psi)
4. This rodi system is designed to produce(move) massive quantities of water(rated at 1000gal/day) thru quickly, hence sacrificing quality results? My RO needs are far below needing huge amounts quickly, currently using no more than 40 gals of RO water every 2 weeks.

Sadly, I don’t know where to go from here. Determining where the existing problems are and fixing them seems daunting.

Starting over with a new quality rodi system might be my best option. I really want to achieve the all zero
ppm quality results mentioned above.

Thanks for your feedback.

Yes. Water as you posted has more than 30 ppm TDS since it has so much sodium, chloride, magnesium and sulfate.

Just a little post RO/DI contamination could account for it. Even a little salt spray dust in the air landing in the RO/DI would do it.
 

clifg

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Do you have a handheld or standalone TDS meter? Seems like your cheapest first step would be to check if your water is coming out, at the end, at 0 TDS. If it checks out twice then your most likely culprit is an inaccurate icp test.
 
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Yes I have a handheld tds meter which I haven’t used again in years. I remember that the readings with it were zero at where the output where the RODI water was exiting & running out vs much higher readings with the same water not moving in a collection jar but immediately just collected. Kinda made me conclude that measuring tds is only accurate with running water?? ie only using inline tds meters in the path of your rodi lines. Actually still wondering if my old observations were correct.

Either way, I will pull out my handheld tds and check my inline results. Thanks
 
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Good to know. Goes to confirm that assumptions are dangerous. Perhaps the collection jar I was using needed to be 100% clean and even void of even a fingerprint. I will re test again using my handheld tds meter and compare to the in-line meters.
 

Randy Holmes-Farley

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Good to know. Goes to confirm that assumptions are dangerous. Perhaps the collection jar I was using needed to be 100% clean and even void of even a fingerprint. I will re test again using my handheld tds meter and compare to the in-line meters.

FWIW, the probe works by sending electrical current between two (or 4) electrodes. if you flow water past it in such a way that there are bubbles or air gaps between the electrodes, then the value may be falsely zero since there may be no path in the water between the electrodes.
 
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Obviously I can’t determine if there are air bubbles or air gaps between the buried tiny inline test probes but with a handheld tds meter I should be able to avoid this problem.
 
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FWIW, the probe works by sending electrical current between two (or 4) electrodes. if you flow water past it in such a way that there are bubbles or air gaps between the electrodes, then the value may be falsely zero since there may be no path in the water between the electrodes.
Randy, I have pulled out my handheld TDS meter and tested the water (stationary) in my RO 75gal storage tank. This RO water was produced 2 weeks ago and at the time of production, my inline TDS meters showed zero ppm.

So should I have been surprised when my hand held DTS meter now reads 15ppm with a sample of water from this RO storage tank? This was the reason why I never trusted a handheld TDS meters many years ago and was of the (misguided) opinion that only newly made running RO water could produce zero ppm water.

Currently I believe that RO storage water would likely never retain anywhere near zero ppm TDS unless both my storage tank and supply lines were kept absolutely kept spotlessly clean. Not likely a achievable expectation given normal household contamination in the surrounding air and also never having the storage tanks tops totally sealed.

My next test will wait to use my handheld TDS meter to compare the readings against my inline meters when my next batch of RO water is actually being made. My expectation is that the quality of my newly made RO water tested with the handheld meter and a totally clean beaker(not the storage tank) will still not read zero ppm due to the non perfect supply line on its way to the beaker (10 ft of supply line).

I wonder if Is it practical to expect that my RO samples sent to a ICP lab would ever come back with elements showing zero ppm.

Sorry for my long out of control thoughts here, but maybe others will find this useful.
 
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