Do I specifically need an RO filter for freshwater before mixing?

[martiniontop]

Soon im going to install a filter to make the drinkable tap water even cleaner (personal reasons not related to the tank) and I was just wondering what reverse osmosis filters do that a normal water filter couldn't do. And if maybe it is possible that a normal filter could work I would also like to know what the filter would have to filter out and keep. On a side note, wouldn't a filter that works with diffusion do the same job as an RO since the opposite of osmosis is diffusion?

Thanks in advance to anyone spending time answering this dumb thought of mine.

(New account since i forgot the login to my old one after too much inactivity)

 

[C_AWOL]

Yes and no.

No an rodi is not necessary if your source water is already generally free of contaminants you don't want (lucky you if thats the case!)

Yes an rodi is necessary because just sediment and carbon filters can't remove everything undesirable (phosphates and silicates for most of us) and its usually less of a headache in the long run to eliminate as many sources as possible at all times (within reason)

 

[ColorMeGone]

RO water, no
RODI water is what you need .

 

[martiniontop]

RO water, no
RODI water is what you need .

So what's the difference and what do yhey usually let/don't let pass through? For the filters we're looking at the companies tell us beforehand that it filters out (xyz) and only lets pass (xyz) so i really just wanna know what filter would be preferable based on what the actual function of an RODI filter is

 

[Bruttall]

RO = Filtered Drinking Water, it still has the trace elements your body needs.
RODI = 0 tds, no trace elements. It's basically just hydrogen and oxygen and is the baseline Standard for Pure Water to mix salt with. I have read that if you feed a potted plant nothing but RO/DI the plant dies, no nutrients in the water. No idea if that is true, never tested it.

 

[ColorMeGone]

So what's the difference and what do yhey usually let/don't let pass through? For the filters we're looking at the companies tell us beforehand that it filters out (xyz) and only lets pass (xyz) so i really just wanna know what filter would be preferable based on what the actual function of an RODI filter is

If you have an RO unit you can always add a DI unit to the outlet of it for your reef tank water.

 

[martiniontop]

Uh... Lets hypothetically pretend that I somehow never knew this and thought that they were the same thing. What would be the next step knowing my hypothetical tank had been running off of RO water this whole hypothetical time. What would be the next step? Could I somehow fix this mishap? The only times all my stock died is when I went on vacation and left them to my neighbor which made the ammonia spike both times he kept the tank and I never seemed to have issues otherwise. Since theres nothing in the tank rn I'm gonna start basically new and put only corals and maybe a tang sometime but no more fish than one are the extra nutrients gonna be an issue?

 

[ColorMeGone]

My drinking RO water has a 2 TDS at the moment and not sure what makes my water have this number but I would not call them nutrients. I also have a RODI system that makes my drinking water have 0 TDS. If you are happy using your RO water then no problem but I would think that having TDS showing and not knowing what they are and that it could always change, I would be on the safe side with adding a DI unit. Your corals will luv you for it. lol

 

[Jamie814]

are the extra nutrients gonna be an issue?

Nobody here can answer this question. Source water varies drastically from one well to another. You would need a water analysis done on your source water. Even then, contaminants change with seasons and time which is why cities have to do regular water testing to make sure it meets safe standards.

 

[Sisterlimonpot]

Uh... Lets hypothetically pretend that I somehow never knew this and thought that they were the same thing. What would be the next step knowing my hypothetical tank had been running off of RO water this whole hypothetical time. What would be the next step? Could I somehow fix this mishap? The only times all my stock died is when I went on vacation and left them to my neighbor which made the ammonia spike both times he kept the tank and I never seemed to have issues otherwise. Since theres nothing in the tank rn I'm gonna start basically new and put only corals and maybe a tang sometime but no more fish than one are the extra nutrients gonna be an issue?

I think what's being missed here are the fundamentals of what a reverse osmosis membrane does, and how water passing through the membrane requires deionization to attract the remaining charged ions to provide a fairly decent starting point to add back the proper elements that are safe for reef tanks.

Yes, most easy reefs and definitely fish only tanks can get away with basic mechanical filtration along with a means to remove chlorine. But...

The issue begins when you don't know what's in your source water and you never account for what harmful elements are you adding to your tank. When issues arise, you now have to put on the top of your list, contamination from your source water. If you start off with "pure water" you're setting yourself up for less headache.

Is it necessary? For most, yes. Especially for those that are still trying to learn everything that encompasses this hobby. Water chemistry is an easy one to control, but if you elect to forego basic water filtration, you need to be prepared to accept the consequences that follow.

It all boils down to having control of what's in your water. The gold standard for this is an RODI unit.

 

[martiniontop]

Thanks a lot for the help everybody I really appreciate it for taking time out of your day and answering my dumb questions. Now for the solution I was thinking of installing an RODI filter and replacing the RO therefore replacing my water top-offs with pure H2O. Since my corals lived pretty healthy for a few months with RO water and im only getting softies until enough RO water evaporates and gets replaced with its better counterpart im positive that they'll live.

Really im very appreciative of your guys's help and hope everyone the best in their projects, much love <3

(PS: if my plan has mistakes that slipped through the cracks please mention them, although im not a complete beginner im not very experienced either)

 

[Jamie814]

Now for the solution I was thinking of installing an RODI filter and replacing the RO therefore replacing my water top-offs with pure H2O.

I'm not sure what you mean by this statement but if you already have an RO unit all you need to do is add the DI canister as the last stage. Just run the RO water line into the DI canister and you now have RO/DI water.

https://www.bulkreefsupply.com/sing...MIm8uVsv_LjgMVi0n_AR2VGw-mEAQYAiABEgIwkPD_BwE

 

[Jamie814]

Since my corals lived pretty healthy for a few months with RO water and im only getting softies until enough RO water evaporates and gets replaced with its better counterpart im positive that they'll live.

Unless you are removing water by water change evaporation will not remove any minerals or impurities that were added from RO water. Minerals do not evaporate, only water evaporates, if they were added to the tank they will stay in the tank unless removed through a water change.

 

[martiniontop]

Yeah sorry i forgot to add water changes too, I meant that slowly but surely all the water would get replaced and that I'd get the DI add on. Really thank you guys much appreciated, hopefully the zoa garden starts once again