Recycling DT water with rodi

[OrionN]

Has nobody ever tried it? Rodi filters are way cheaper then salt, doing a 20% 140 gallon water change. 695gal total volume.
Guess I'll just try it, what's the worst thing that can happen? Have to buy new membrane, seals, filters, etc. Or even a new rodi all together.
Best case scenario, all lvls near zero, add a little salt, then automate it.

Lets for get the DI for now, just RO.
RO remove impurities from the water result in fresh water. It does not result in sea water. You still need to buy salt to mix new salt water. Furthermore, lets say your RO unit recover 10 gal for every 100 gal you run through it and you have a really best RO membrane which rejected 99% of the impurities. You change 300 gal of your water and run it through it. Your water have 35 ppt impurities which is normal for a reef tank. After the first run through the RO filter push by your brand new booster pump, you recovered 30 gal which have .35 ppt of impurities which is 350 ppm. This is even worst than your tab water (which is about 250 ppm) so you decided to run it though the RO filter again. After the second time around you recovered 3 gal, with impurities of 3.5 ppm. You decided to run this though an DI unit which result in 3 gal of pure water at 0 ppm impurities.

After all that trouble you have 3 gal of water to mix with IO reef crystal to make salt water.

I don't think you should attempt. There is something you did not consider. Reefers as a whole, are the most innovative group of people. After all these years, nobody did this becasue it is just not a worthwhile idea.

 

[Listant09]

It's funny how some dont look at the question at hand, can water from the water change be recycled, through an rodi, Admann answered it best, just need to find a membrane capable of letting dissolved salt (sodium chloride) through
After which the filters would remove all other contaminants, and the de-ionization part of the rodi wouldnt be used, so reverting to just an RO filter with a membrane to allow the sodium chloride through, applying pressure to the more concentrated (dirtier) side of a semipermeable membrane, water molecules are pushed back across the membrane to the less concentrated (cleaner) side, resulting in more purified water. typically removing 90-99% of most contaminants. DI filters are not physical filters with a pore size and cannot remove bacteria or particulates.

Thanks for all your help

 

[OrionN]

take the deionized (DI) out of the process as this only takes the calcium and iodine out of the water, so in turn it would be a reverse osmosis system, with larger holes in the membrane to allow the dissolved salt through, the rest of the contaminants should be stopped by the filters

This is wrong. RO removes ionized impurities in water. That what the membrane does, it pushes charged particle away. It does not filter because the physical size of the holes in the membrane. Rather the membrane rejects charged molecules.

You have a fundamental error in your thinking. RO rejects almost all impurities and the DI removes the minor amount and release OH- for the negative charge particles and H+ for positive charge particles result in just pure water.

 

[Listant09]

Lets for get the DI for now, just RO.
RO remove impurities from the water result in fresh water. It does not result in sea water. You still need to buy salt to mix new salt water. Furthermore, lets say your RO unit recover 10 gal for every 100 gal you run through it and you have a really best RO membrane which rejected 99% of the impurities. You change 300 gal of your water and run it through it. Your water have 35 ppt impurities which is normal for a reef tank. After the first run through the RO filter push by your brand new booster pump, you recovered 30 gal which have .35 ppt of impurities which is 350 ppm. This is even worst than your tab water (which is about 250 ppm) so you decided to run it though the RO filter again. After the second time around you recovered 3 gal, with impurities of 3.5 ppm. You decided to run this though an DI unit which result in 3 gal of pure water at 0 ppm impurities.

After all that trouble you have 3 gal of water to mix with IO reef crystal to make salt water.

I don't think you should attempt. There is something you did not consider. Reefers as a whole, are the most innovative group of people. After all these years, nobody did this becasue it is just not a worthwhile idea.

I guess you didnt completely understand the question at hand, the question is about cleaning the water and leaving the sodium chloride(salt) in it
In other words it's not about what your typical off the shelf rodi filter is doing, its can an rodi filter water and still leave sodium chloride, so the answer would be yes theoretically it could with a membrane that has large enough holes to allow the dissolved sodium chloride (salt) through

So to say this isnt wise, would be like telling einstein he was crazy, to try and figure out the theory of relativity, which people did, but now hes considered a genius, ...the issue of your relativity to the solution of filtering water but allowing dissolved sodium chloride to remain is only relevant to someone with a small tank 200gal or less, as a 20 gal water change costs pennies, to someone with a large tank or tanks it makes a lot of sense to do, dosing is relatively cheap, salt on the other hand in large quantities such as pallets of it, is fairly expensive

 

[Listant09]

This is wrong. RO removes ionized impurities in water. That what the membrane does, it pushes charged particle away. It does not filter because the physical size of the holes in the membrane. Rather the membrane rejects charged molecules.

You have a fundamental error in your thinking. RO rejects almost all impurities and the DI removes the minor amount and release OH- for the negative charge particles and H+ for positive charge particles result in just pure water.

THINK AGAIN

RO and DI filters use different physical reactions to clean water. Reverse Osmosis (RO) is often used to partially clean-up tap water to make it roughly 90% to 99% pure. Deionization (DI) filters exchange positive hydrogen and negative hydroxyl molecules for positive and negative contaminant molecules in water. DI filtering and other processes are sometimes referred to as "water polishing."

To answer the question more specifically, the individual technologies need to be understood.

Reverse Osmosis (RO) is the opposite of a natural process simply called osmosis. Osmosis is the movement of water molecules across a semipermeable membrane. The process naturally moves water from a low ion concentration to a higher ion concentration across a semipermeable membrane to create reverse osmosis water. This natural process is used by our bodies to get water to our individual cells.

By applying pressure to the more concentrated (dirtier) side of a semipermeable membrane, water molecules are pushed back across the membrane to the less concentrated (cleaner) side, resulting in more purified water. This process is called Reverse Osmosis and can typically remove 90-99% of most contaminants. It is not perfect, but is a very cost effective technology; the RO Membrane can last for years if used properly. Reverse Osmosis is often used to partially clean-up tap water before any other purification technology is used to remove the remaining 1-10% of contaminants.

Deionization (DI) filters have many names: Ion Exchange, Strong Acid/Strong Base, Polishing, Nuclear Grade. Nuclear grade DI filters can remove Inorganic chemicals down to very low parts per billon (PPB) levels. This makes them excellent for producing Ultra-Purified (Type I, 18.2 Megohm) water. Water of this quality is used with the most sensitive laboratory analytical instruments, which are designed to detect chemicals at extremely low concentration levels.

Deionization filters function by exchanging positive hydrogen and negative hydroxyl molecules for the positive and negative contaminant molecules in the water. Positive chemicals, like calcium, exchange places with the hydrogen molecules and negative chemicals, like iodine, exchange places with the hydroxyl molecules. Over time, positive and negative contaminants in the water displace all the active hydrogen and hydroxyl molecules on the DI resin and the filter must be replaced. Regeneration of the deionization filter is possible, but only in an industrial environment setting.

Deionization is an on-demand process supplying purified water when needed. This is important because water at this extreme purity level degrades quickly. The nuclear grade deionization resin or polishing mixed bed resin removes almost all the inorganic contaminants in the water increasing the resistivity of the water to a maximum of 18.2 megohm-cm. However, deionization alone does not remove all types of contaminants like dissolved organic chemicals. Deionization filters are not physical filters with a pore size and cannot remove bacteria or particulates.

 

[Listant09]

This is wrong. RO removes ionized impurities in water. That what the membrane does, it pushes charged particle away. It does not filter because the physical size of the holes in the membrane. Rather the membrane rejects charged molecules.

You have a fundamental error in your thinking. RO rejects almost all impurities and the DI removes the minor amount and release OH- for the negative charge particles and H+ for positive charge particles result in just pure water.

It's your fundamental thinking not mine, pretty sure I know what each does

 

[Daddy-o]

Fyi the sodium chloride isnt removed from

So you dont think your water changes remove nitrates, nitrites, phosphates, etc.
Like I said, I dose, so doing the water change isnt about adding trace elements, it's about keeping water quality high, dont get me wrong, some trace elements are returned with the 20% water change and new salt, but that's not why I'm doing the water change
But if I can recycle the water to keep the calcium, iodine, sodium chloride (salt) that's less salt needed, hence benefits other things as well as not having to run calcium reactor as much etc.

I am sure that nitrates and phosphates do get removed with a water change but I keep their numbers where I want with bacteria, carbon dosing, and skimming/flow. I change my water to add back in the elements that are being depleted.
Cheers! Mark

 

[OrionN]

@Listant09

Larger, huge molecules like protein will filter out due to size. So are bacterial and virus, but dissolved salt get eliminated due to their ionic property not size. That is why Hydrogen sulfide (H2S) can pass through the membrane unimpeded while Na+, which is much smaller cannot.
If you don't believe me, you can do your search and see that hydrogen sulfide does not get filter out with RO.

Definitely Na+ and Cl_ get eliminated and very easy. In hard water situation, there the RO membrane get ruin quickly due to CaCO3 deposit on the membrane, it is recommended that we use water softener which replace CaCO3 with NaCl or KCl. Na Cl virtually get eliminated near 100%. Like you also pointed out before. RO membrane are use to desalinated salt water, but this result in fresh, pure water, not salt water.

Even if you can get a membrane that magically spare Na Cl, what about all the other major and minor elements and compounds. Our aquarium water have all kinds of other impurities from the majors compounds sulfate (SO2 4−), magnesium (Mg 2+), calcium (Ca 2+), and potassium (K+), HCO3- and CO3 2- and all the minor compounds and elements. There is just no to replace these. Cheapest to get RO to remove all the impurities from tap water, then add synthesized salt.

There are a few people maintain great reeftanks with no water change. I think if you think that salt are too expensive, maybe you should look into how these people do this and thinking of no water change reef tank yourself

Cheers.

 

[krash7172]

It's absolutely possible to recycle DT water. An RO filter won't work unless it's huge. It's one of the last options used to treat water with high organics and salt. Just not efficient.

 

[Listant09]

@Listant09

Larger, huge molecules like protein will filter out due to size. So are bacterial and virus, but dissolved salt get eliminated due to their ionic property not size. That is why Hydrogen sulfide (H2S) can pass through the membrane unimpeded while Na+, which is much smaller cannot.
If you don't believe me, you can do your search and see that hydrogen sulfide does not get filter out with RO.

Definitely Na+ and Cl_ get eliminated and very easy. In hard water situation, there the RO membrane get ruin quickly due to CaCO3 deposit on the membrane, it is recommended that we use water softener which replace CaCO3 with NaCl or KCl. Na Cl virtually get eliminated near 100%. Like you also pointed out before. RO membrane are use to desalinated salt water, but this result in fresh, pure water, not salt water.

Even if you can get a membrane that magically spare Na Cl, what about all the other major and minor elements and compounds. Our aquarium water have all kinds of other impurities from the majors compounds sulfate (SO2 4−), magnesium (Mg 2+), calcium (Ca 2+), and potassium (K+), HCO3- and CO3 2- and all the minor compounds and elements. There is just no to replace these. Cheapest to get RO to remove all the impurities from tap water, then add synthesized salt.

There are a few people maintain great reeftanks with no water change. I think if you think that salt are too expensive, maybe you should look into how these people do this and thinking of no water change reef tank yourself

Cheers.

I already said I dose all trace elements, so that's not the issue, it was just a logical question if the water can be filtered leaving the salt, a pool filter is out of the question as the majority add chlorine, so at this stage it's a matter of contacting DOW or Dupont who make industrial membranes and find out if the membrane can be made to allow the salt through, it's all in the permeable membrane, if it cant work, so be it, that's why I get pallets of reef salt, and have an industrial rodi with 1000 gal of stored salt water on hand, like I said it's just a thought, I'm sure it can be done, but at what cost to do it? Essentially it would change the home aquarium hobby as we know it. Rodi systems were never meant to leave the salt in the water, that's just not what they were designed for, but I'm sure a few tweaks here and there, it could be done.
Why hasn't it been done yet? It's not a necessity to the world to filter salt water for the aquarium hobby, it is though a necessity to filter seawater to drink.

 

[krash7172]

Energy to convert high nutrient salt water to drinkable isn't economically viable with current technology. Possible, yes.

 

[Listant09]

@Listant09

Larger, huge molecules like protein will filter out due to size. So are bacterial and virus, but dissolved salt get eliminated due to their ionic property not size. That is why Hydrogen sulfide (H2S) can pass through the membrane unimpeded while Na+, which is much smaller cannot.
If you don't believe me, you can do your search and see that hydrogen sulfide does not get filter out with RO.

Definitely Na+ and Cl_ get eliminated and very easy. In hard water situation, there the RO membrane get ruin quickly due to CaCO3 deposit on the membrane, it is recommended that we use water softener which replace CaCO3 with NaCl or KCl. Na Cl virtually get eliminated near 100%. Like you also pointed out before. RO membrane are use to desalinated salt water, but this result in fresh, pure water, not salt water.

Even if you can get a membrane that magically spare Na Cl, what about all the other major and minor elements and compounds. Our aquarium water have all kinds of other impurities from the majors compounds sulfate (SO2 4−), magnesium (Mg 2+), calcium (Ca 2+), and potassium (K+), HCO3- and CO3 2- and all the minor compounds and elements. There is just no to replace these. Cheapest to get RO to remove all the impurities from tap water, then add synthesized salt.

There are a few people maintain great reeftanks with no water change. I think if you think that salt are too expensive, maybe you should look into how these people do this and thinking of no water change reef tank yourself

Cheers.

In other words it's like most things, once its figured out it costs a lot, but after refining the process it gets cheaper in the long run, as most things do once industrialized, ie. Led tvs, water pumps, etc. etc.

 

[Listant09]

I am sure that nitrates and phosphates do get removed with a water change but I keep their numbers where I want with bacteria, carbon dosing, and skimming/flow. I change my water to add back in the elements that are being depleted.
Cheers! Mark

And I'm guessing you have a relatively small tank or total water volume (TWV) where that's easy to do, I have 100's if not 1000's of frags growing, I have a a 535gal, a cpl 250's, a cpl 150's, a 2 1/2 car garage with nothing but frag tanks, so keeping a little refugium for your little tank may work for you, were talking apples and oranges between our setups, you have an apple tree I have acres of orange trees... when you jump up over 500 gal TWV then give me your input, I'm looking for people to who have MONSTER REEF SYSTEMS to give input, not someone with a 125 to try to tell me how it is

 

[HOOPDEEZ]

Sounds like you know the answer dude, go for it!

 

[fishguy242]

imo you seem to know what you are doing ,just do it ,tell us how it works out, i like buying pallets of salt 25% cheaper ,happy reefing ,would be interested in results

 

[fishguy242]

Sounds like you know the answer dude, go for it!

i was a hair slow on the trigger there lol

 

[Listant09]

imo you seem to know what you are doing ,just do it ,tell us how it works out, i like buying pallets of salt 25% cheaper ,happy reefing ,would be interested in results

I'm definitely going to look into it, I'm sure it can be done, definitely worth buying a pallet of salt for the discount bulk is always cheaper, especially from a wholesaler

 

[fishguy242]

skip the wholesaler ,buy direct 1 less upcharge!!

 

[Listant09]

skip the wholesaler ,buy direct 1 less upcharge!!

Technically I do buy direct, I get a pallet or pallets with a big white sack on it with 2400 lbs of salt on it, it's a little over 8000gal of mixed water per bag

 

[Listant09]

skip the wholesaler ,buy direct 1 less upcharge!!

How I get my salt