Bent
I got nothin'
You are correct.
Another boil advisory
- Thread starter Airborne12B
- Start date
You are correct.
nereefpat
New member
Ha. I thought you were just making fun of me.
Reverse osmosis has been used to desalinate seawater for drinking since before I was born. it most certainly removes ions. A certain percentage is left over, due to the way RO works. That small percentage is polished by the di cartridge.
As far as the rest of it, the pore size of membranes, the size of bacteria, the lengths of microns, nanometers, angstroms, etc can be easily found online.
Reverse osmosis has been used to desalinate seawater for drinking since before I was born. it most certainly removes ions. A certain percentage is left over, due to the way RO works. That small percentage is polished by the di cartridge.
As far as the rest of it, the pore size of membranes, the size of bacteria, the lengths of microns, nanometers, angstroms, etc can be easily found online.
CStrickland
New member
Yeah, hence the edit 
The way rodi can desalinate water is that a lot of the sodium is attached to water molecules pretty strongly. Together they are too large to pass the membrane. It's not that the membrane is so fine that it doesn't allow Na to pass, it's just too fine to allow saltywater through. Water, or bare Na ions do pass. That's where the di comes in. So, it's not accurate to say that an ro membrane catches such tiny ions as Na, so it will also catch bacteria. If that were true I don't think water would get through either, as it is also larger than Na ions.
That's for our purposes. I think big water treatment desalination works much differently, strong membranes and very high pressure iirc.
The way rodi can desalinate water is that a lot of the sodium is attached to water molecules pretty strongly. Together they are too large to pass the membrane. It's not that the membrane is so fine that it doesn't allow Na to pass, it's just too fine to allow saltywater through. Water, or bare Na ions do pass. That's where the di comes in. So, it's not accurate to say that an ro membrane catches such tiny ions as Na, so it will also catch bacteria. If that were true I don't think water would get through either, as it is also larger than Na ions.
That's for our purposes. I think big water treatment desalination works much differently, strong membranes and very high pressure iirc.
nereefpat
New member
Yeah, hence the edit
The way rodi can desalinate water is that a lot of the sodium is attached to water molecules pretty strongly. Together they are too large to pass the membrane. It's not that the membrane is so fine that it doesn't allow Na to pass, it's just too fine to allow saltywater through. Water, or bare Na ions do pass. That's where the di comes in. So, it's not accurate to say that an ro membrane catches such tiny ions as Na, so it will also catch bacteria. If that were true I don't think water would get through either, as it is also larger than Na ions.
That's for our purposes. I think big water treatment desalination works much differently, strong membranes and very high pressure iirc.
Yes, you are right on most of that. I shouldn't have stated my bacteria salt argument in that way. Water molecules are smaller in both weight and diameter than Na ions, although not by much. A water molecule is nearly the smallest matter there is, other than H2. And the RO stage removes most, if not nearly all, salts including small ones.
My point was that bacteria are 1000-10,000 times too big to make it through RO.
BTW, Thanks to you both for keeping this, for the most part, respectful and civil.
PirateLove
New member
Go buy the green top gallon waters from Walmart. Zero tds.
Sweet! Thanks for the discussion folks. I got some seriously great things to think about. I had made my last batch for the water change a few days before the advisory, is it likely there could now be bacteria growing in my RODI? I would think not, but these guys suck so hard who knows how long the water was unsatisfactory before they caught it. The city manager resigned, but a lot of people still want blood lol. They're all up in arms saying the city should pay their water bills to make up for it. I'm actually saving money during this boil so I don't feel motivated to join them. I'm just trying to make sure the tank makes it out okay.
As for the debate, if I understand what happens to bacterial cells in aqueous solutions correctly, a cell's survival essentially comes down to whether or not it is hydrophilic or hydrophobic. Since homeostasis is a thing, we know that a freshwater bacteria in saltwater would be effected by plasmolysis, but this is often only temporary and wouldn't necessarily effect division. In the case of a gram negative cell like E.coli, plasmolysis would be inhibited, which would further lead us to believe in its ability to survive in saltwater. To further support this, we know that E.coli's growth is not inhibited in 10% NaCl which is much higher than the 3% average of the ocean. Based on my understanding microbiology (or lack thereof), and the research that has been done, I believe that E.coli can survive in saltwater which is the source of my caution.
Further reading:
https://www.scribd.com/doc/11337868/Optimal-Conditions-for-the-Growth-of-E-Coli
http://jb.asm.org/content/98/2/335.full.pdf
http://www.ncbi.nlm.nih.gov/pubmed/23790382
http://pubs.acs.org/doi/abs/10.1021/bi0109515
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2696358/
http://aem.asm.org/content/55/8/2017.full.pdf
http://bio.huji.ac.il/upload/59(1).pdf
As for the debate, if I understand what happens to bacterial cells in aqueous solutions correctly, a cell's survival essentially comes down to whether or not it is hydrophilic or hydrophobic. Since homeostasis is a thing, we know that a freshwater bacteria in saltwater would be effected by plasmolysis, but this is often only temporary and wouldn't necessarily effect division. In the case of a gram negative cell like E.coli, plasmolysis would be inhibited, which would further lead us to believe in its ability to survive in saltwater. To further support this, we know that E.coli's growth is not inhibited in 10% NaCl which is much higher than the 3% average of the ocean. Based on my understanding microbiology (or lack thereof), and the research that has been done, I believe that E.coli can survive in saltwater which is the source of my caution.
Further reading:
https://www.scribd.com/doc/11337868/Optimal-Conditions-for-the-Growth-of-E-Coli
http://jb.asm.org/content/98/2/335.full.pdf
http://www.ncbi.nlm.nih.gov/pubmed/23790382
http://pubs.acs.org/doi/abs/10.1021/bi0109515
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2696358/
http://aem.asm.org/content/55/8/2017.full.pdf
http://bio.huji.ac.il/upload/59(1).pdf
nereefpat
New member
Can't grow in RODI. There is no carbon source. They need glucose, ethanol, or something. They would also probably lyse, due to their cells being much saltier than the surrounding water. Water moves into the cells because of the osmotic gradient.
I believe the terms you are searching for are: hypertonic, hypotonic, and isotonic. In RODI water, the outside solution is hypotonic. In seawater, the outside solution is hypertonic.
CStrickland
New member
Pseudomonas aeruginosa populate distilled water quite well. I don't see why stagnant rodi would be different.
nereefpat
New member
If by populate you mean survive in, then that is possible. He asked about growth. Needs carbon: glucose, ethanol, acetate, etc
CStrickland
New member
http://science.sciencemag.org/content/173/3999/836.long
That's from the 70's though so idk
More to the point, I'm not sure your distinction is meaningful. Idk how many you'd need to get sick, but you can get very sick from this bug and it's resistant to multiple antibiotics. That's why I'd favor the "better safe than sorry" approach. That cootie spreads well when aerosolized, so I guess you wouldn't need to drink the water either.
Further, exposure to light could provide a carbon source as well. It wouldn't need to be glucose in the water.
Bent
I got nothin'
fun fact:
Hospitals have gone away from using traditional bath basins. (The pink plastic tubs).
A large study was performed by swabbing dry multi-use single patient basins and culturing them.
100%. Read, all of them, out of thousands of samples grew staph. And not the good staph. The methicillin resistant kind of staph. MRSA.
And that was in dry basins. Go figure.
OrionN
Moved on
You must be in Corpus Christi
nereefpat
New member
Hey, nothing wrong with the 70s. I hear they were fun.
After much searching, I found the entire paper. It seems there was a contamination in a pediatric ward of a hospital. they found bacteria cells in the reservoirs of mist therapy units. They plated the contaminated water on soy agar. Things grew. They diluted and isolated Pseudomonas from what grew. Then, what was grown on agar was put back in a sterile filtered mist therapy water from before. The P. grew, living off what was in the agar and what was in the therapy water.
The point was that viable cells were in the reservoirs, even though the water in the reservoirs was initially distilled. And also cells that had recently spent time in the reservoirs hit log growth sooner than cells that had recently spent generations in soy agar, showing the adaptability if cells to the reservoir water.
As for light, are you suggesting sugars could be made by algae in the water, then used by bacteria? I'm sure you know organisms like Pseudomonas and E. coli aren't autotrophs
Yes, they were indeed. Thank you. The point, however, is still unchanged, and I don't think that we can just say that a solution is always one of those. Doesn't it change depending on what is in the solution? For instance, my house is always 75 degrees but I adjust that number depending on who is coming over for dinner. Even my wife experiences that same temperature differently that I do.
Semantics. The discussion is centered around a bacteria's viability in the RO/DI and in the tank-water. I'm trying to determine if I should do something to my RO/DI unit after this water boil, or not. Keep in mind that it had not been used for a few days prior to the advisory being issued.
Yep, what's your solution Minh? I went to Wal-Mart yesterday to grab some of the green cap water that was mentioned, but the only thing they have is baby water with "minerals added for taste." The problem is the whole city is buying up all the water lol.
OrionN
Moved on
I just disregarded the boil advisory, using my RO system for drinking water. My membrane is about 2 years old. I plan to change all the filter including the membrane, after flush the whole system with chlorine after the boil advisory is over.
Bent
I got nothin'
My advice stands and is likely the same advice the water company will give you. Don't use your water until the boil advisory is over, boil or sanitize anything that was in contact with the water during the advisory.
Hepatitis, amoebic dysentery, and salmonella are not fun things to contract.
Audentes Fortuna Juvat lol
I'm in this boat. I got amoebic dysentery when I first arrived in Afghanistan. I'm not trying to get that again. I was trying to be all :uzi: but my guts were like :blown:. So if my RO/DI was not used during this advisory, it should be fine? I've been taking all appropriate precautions for myself and my wife, but I'm going to have to shut of my pump soon or it will start screaming if I can't top it off with something.
dkeller_nc
New member
Airborne: There are a lot of scientific inaccuracies on this thread. but since those inaccuracies are irrelevant to your question(s), here's the bottom line:
Your RODI system has bacteria and bacterial spores in it all the time upstream of the RO membrane. And there's a near 100% chance that it has detectable bacteria downstream of the RO membrane in your DI cartridge and tubing as well. This is irrespective of "boil water advisories" from your water department. There is no reason that you cannot use this for your reef tank - I can guarantee you that 100% of us 100% of the time use RODI for water changes and top-offs that have detectable bacteria in it. Those bacteria will not cause an issue. One of the reasons is that your reef tank has several million bacteria per mL under normal operation. Very slightly adding to that population with a 100 bacteria per mL in your RODI will make utterly no difference whatsoever.
Keep in mind that your water department is issuing an advisory for any or all of the following reasons:
1) Insufficient chlorination/chloramination detected at various sampling points in the system.
2) Detection of total and fecal coliform bacteria above the drinking water testing limit in municipal water systems. While the limit is "zero" for total and fecal coliforms, this does not mean that all samples must be negative - the limit is 5% of the samples showing the presence of coliforms.
3) An actual system break where air can enter the system.
Keep in mind that an average human ingests quite a lot of organisms everyday that could potentially cause disease. But if you have a normal immune system, it typically requires ingestion of a truly contaminated liquid/solid with thousands to millions of these organisms.
That doesn't mean I'm suggesting to you to not boil water for drinking or brushing your teeth (or drink bottled water, or sterilize the municipal water by other means such as filtration or addition of chlorine). But you shouldn't panic - it is definitely possible your municipal system has a testing issue, not necessarily a water system issue.
Your RODI system has bacteria and bacterial spores in it all the time upstream of the RO membrane. And there's a near 100% chance that it has detectable bacteria downstream of the RO membrane in your DI cartridge and tubing as well. This is irrespective of "boil water advisories" from your water department. There is no reason that you cannot use this for your reef tank - I can guarantee you that 100% of us 100% of the time use RODI for water changes and top-offs that have detectable bacteria in it. Those bacteria will not cause an issue. One of the reasons is that your reef tank has several million bacteria per mL under normal operation. Very slightly adding to that population with a 100 bacteria per mL in your RODI will make utterly no difference whatsoever.
Keep in mind that your water department is issuing an advisory for any or all of the following reasons:
1) Insufficient chlorination/chloramination detected at various sampling points in the system.
2) Detection of total and fecal coliform bacteria above the drinking water testing limit in municipal water systems. While the limit is "zero" for total and fecal coliforms, this does not mean that all samples must be negative - the limit is 5% of the samples showing the presence of coliforms.
3) An actual system break where air can enter the system.
Keep in mind that an average human ingests quite a lot of organisms everyday that could potentially cause disease. But if you have a normal immune system, it typically requires ingestion of a truly contaminated liquid/solid with thousands to millions of these organisms.
That doesn't mean I'm suggesting to you to not boil water for drinking or brushing your teeth (or drink bottled water, or sterilize the municipal water by other means such as filtration or addition of chlorine). But you shouldn't panic - it is definitely possible your municipal system has a testing issue, not necessarily a water system issue.
Bent
I got nothin'
Yeah I mean if you are 100% sure the unit didn't get any of the affected water in it, you should be in the clear. But if you have any question, I would play it way way waaay on the safe side. :fish1:
