Recycling DT water with rodi

[Listant09]

Just curious if anyone has tried to take the old water from doing a water change and ran it back through the rodi?
Would the salt ruin the rodi? Or would it actually not remove any of the salt from said water, just removing contaminants? As an rodi isn't technically a desalination devise.

 

[Daddy-o]

Would probably trash the membrane

 

[Listant09]

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.

 

[Admann]

Offshore our watermakers were RO/DI, 10,000 gpd each unit x2. We made 0 tds from seawater. Whether or not the membrane materials are the same or not for salt and fresh, I don't know, never asked the question. I can tell you this though, I have made a lot of fresh water over the years out of seawater.

 

[Listant09]

So it is theoretically possible to work, I just need to figure out if the membrane will hold up, or for how long it will last before replacing it. I'm guessing not long with saltwater, any clue what commercial rodi those were?
Thanks Admann for the insite

 

[LegendaryCG]

Considering how much water is rejected I can’t imagine you’d end up with very much recycled water.

 

[Admann]

So it is theoretically possible to work, I just need to figure out if the membrane will hold up, or for how long it will last before replacing it. I'm guessing not long with saltwater, any clue what commercial rodi those were?
Thanks Admann for the insite

The membranes were 6"x48" and there were if I remember right at least 12 membranes in each unit, made by DOW

 

[Listant09]

The membranes were 6"x48" and there were if I remember right at least 12 membranes in each unit, made by DOW

Awesome, I'll look into it... thanks again

 

[DarkSky]

Putting saltwater through a RODI unit will give you RODI water, no salt or other minerals will be present. All you'll be doing is burning through your filters and media much, much faster.

Bad idea.

 

[ZoWhat]

Is the price of tap water coming into your place the cost of highend bourbon or smthg? Lololololololololol

Reminds me of the opening scene of the movie WaterWorld

Thirsty?

 

[Listant09]

Considering how much water is rejected I can’t imagine you’d end up with very much recycled water.

Putting saltwater through a RODI unit will give you RODI water, no salt or other minerals will be present. All you'll be doing is burning through your filters and media much, much faster.

Bad idea.

But like a swimming pool using salt water, its filtered, leaving the dissolved salts in the water, so hence using the rodi to do the same process filtering the water, but leaving the dissolved salt would be the same thing, in other words, the membrane in the rodi would have to be changed to allow the salt to pass through, the actual filters on the rodi would or should allow the dissolved salt through as well.
A swimming pool filter is essentially the same as an rodi.

 

[DarkSky]

But like a swimming pool using salt water, its filtered, leaving the dissolved salts in the water, so hence using the rodi to do the same process filtering the water, but leaving the dissolved salt would be the same thing, in other words, the membrane in the rodi would have to be changed to allow the salt to pass through, the actual filters on the rodi would or should allow the dissolved salt through as well.
A swimming pool filter is essentially the same as an rodi.

Just because both have the word filter in the name, they are in no way the same. RO membranes have many orders of magnitude smaller openings than a pool filter. They're also not running DI.

 

[Listant09]

Is the price of tap water coming into your place the cost of highend bourbon or smthg? Lololololololololol

Reminds me of the opening scene of the movie WaterWorld

Thirsty?

Lol, no but I have that tank, a couple 240's, a 150 and frag tanks, plus cichlid tanks, all together I have around 6000 gal of water, so I use alot of water, not to mention I live in the Florida keys water is a little spendy over $6 for a 1000 gal

 

[Listant09]

Just because both have the word filter in the name, they are in no way the same. RO membranes ha e many orders of magnitude smaller openings than a pool filter. They're also not running DI.

Yeah I get that, so in other words finding a membrane that let's dissolved salt through is the key, it's not rocket science, again like a swimming pool filter, not my first rodeo with filters

 

[Osric]

A swimming pool filter is essentially the same as an rodi.

I think what people are trying to tell you is that a swimming pool filter and an RO/DI filter have in common the word “filter” and not much else.

Specifically, DI stands for “de-ionization” the removal of ions from the water. Salt water contains sodium and chloride ions, and de-ionization will remove them. You’ll have to add salt again to the filtered water, which will be a fraction of the water you put through the RO/DI filter. It’ll cost you more in filtration and the same in salt, as well as electricity. So what you’re proposing is expensive and not useful.

Lastly, even if you were right and you could run the tank water through a filter — say a swimming pool filter — without removing the salt, you wouldn’t have added back in the trace elements that we don’t dose and your life has used up. Magnesium being the largest among these, but there are others, that we rely on fresh salt water re-introducing into the ecosystem. It is my personal belief that the reason so many people have “old tank syndrome” or crashes after their tank being “perfect” for months is that they slack on water changes, not remembering that new saltwater is important for their corals.

 

[Listant09]

Just because both have the word filter in the name, they are in no way the same. RO membranes have many orders of magnitude smaller openings than a pool filter. They're also not running DI.

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

 

[Osric]

Just because both have the word filter in the name, they are in no way the same. RO membranes have many orders of magnitude smaller openings than a pool filter. They're also not running DI.

If you live in the keys NSW might be a realistic option. I’m not familiar with the pros and cons but at least I know that people have done it successfully.

 

[Listant09]

I think what people are trying to tell you is that a swimming pool filter and an RO/DI filter have in common the word “filter” and not much else.

Specifically, DI stands for “de-ionization” the removal of ions from the water. Salt water contains sodium and chloride ions, and de-ionization will remove them. You’ll have to add salt again to the filtered water, which will be a fraction of the water you put through the RO/DI filter. It’ll cost you more in filtration and the same in salt, as well as electricity. So what you’re proposing is expensive and not useful.

Lastly, even if you were right and you could run the tank water through a filter — say a swimming pool filter — without removing the salt, you wouldn’t have added back in the trace elements that we don’t dose and your life has used up. Magnesium being the largest among these, but there are others, that we rely on fresh salt water re-introducing into the ecosystem. It is my personal belief that the reason so many people have “old tank syndrome” or crashes after their tank being “perfect” for months is that they slack on water changes, not remembering that new saltwater is important for their corals.

I'm not a complete idiot, I understand that they are two different filters, a pool filter is typical just a sand filter, or paper filter, not stopping the contaminated water of nitrates, etc. That rodi filter will , "Di" the deionized part of an rodi removes calcium and iodine, the calcium is useful so in other words, just using a reverse osmosis filter, with a larger membrane to allow the dissolved salts through yet still removing the rest of the contaminates in the filters would be beneficial

I run an apex dosing, so removing trace elements isnt an issue, they are replaced regularly, this is about trying to cut down on salt purchased, there has to be a way to remove all contaminants from water without removing the salt content (salinity) which is technically sodium chloride
Maybe I'm asking for to much from an RO/DI filter

 

[Daddy-o]

I don't do water changes to remove any thing from my reef. I do them to add elements that have been used by my critters/corals. What kind of crap are you trying to get out of your water?

 

[Listant09]

I think what people are trying to tell you is that a swimming pool filter and an RO/DI filter have in common the word “filter” and not much else.

Specifically, DI stands for “de-ionization” the removal of ions from the water. Salt water contains sodium and chloride ions, and de-ionization will remove them. You’ll have to add salt again to the filtered water, which will be a fraction of the water you put through the RO/DI filter. It’ll cost you more in filtration and the same in salt, as well as electricity. So what you’re proposing is expensive and not useful.

Lastly, even if you were right and you could run the tank water through a filter — say a swimming pool filter — without removing the salt, you wouldn’t have added back in the trace elements that we don’t dose and your life has used up. Magnesium being the largest among these, but there are others, that we rely on fresh salt water re-introducing into the ecosystem. It is my personal belief that the reason so many people have “old tank syndrome” or crashes after their tank being “perfect” for months is that they slack on water changes, not remembering that new saltwater is important for their corals.

Fyi the sodium chloride isnt removed from

I don't do water changes to remove any thing from my reef. I do them to add elements that have been used by my critters/corals. What kind of crap are you trying to get out of your water?

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.