Why RODI

DeepSouth · Aug 9, 2019

I do have a RODI unit, so I am not trying to cut corners, but what are the specific reasons RODI is used in marine but not freshwater?

Is it just because corals are more sensitive?

Amboss72 · Aug 9, 2019

In reef aquariums we want to strip the water down to zero total dissolved solids in the best case scenario. We do this just to start with a clean slate if you will. In the reef aquarium, water that isn’t RODI just opens the door for many issues that we can avoid altogether if we know the water we start with has zero tds. I have both fresh and reef aquariums and frankly I just use rodi water on both of them as I’ve found I have far less problems altogether. I have seen others try to navigate reef aquariums with water that isn’t rodi and I can say they deal with so many issues that could be avoided altogether if they just started with zero tds water. Happy reefing!

Amboss72 · Aug 9, 2019

Yes, the reef aquarium is much more sensitive to water chemistry parameters. Simply put, you don’t know what’s in your tap water. It would require many different test kits to just figure out what’s causing a problem if a problem manifests. Certainly you can try tap water as maybe we are all just hyper focused on zero tds. If it proves that tap water works just as well as rodi water I would be saving myself and my clients a lot of money on creating zero tds water. I can only speak to my experience but I can say I had a client who said they were topping their reef tank off with only rodi water. I came to find out this wasn’t the case. Simply put I was constantly struggling with Cyanobacteria and algae issues. This wasn’t an issue in the other tanks I maintained. I will always maintain that I know I don’t know. I’m always open to new ways. Give none rodi water a try and share your experience with the rest of us.

DeepSouth · Aug 10, 2019

Amboss72 said:
Give none rodi water a try and share your experience with the rest of us.

I really don't have the intestinal fortitude to be a test case at this time. I was curious what problems those with experience observed. Thanks for your input. I find it interesting that there would be more algae issues with tap water.

leewish · Aug 10, 2019

Also think about the cost of marine life versus fresh. Not that I am belittling the fresh animals but with so much more captive breeding in fresh those animals have become used to the additives in the water. Many of the salt fish are being wild caught and tossed into a box of water. Giving them pristine conditions to have a chance to thrive versus being exposed to tap water contaminants is a huge change for them.

I do have a friend who uses RODI for his discus.

Billdogg · Aug 10, 2019

Can you keep a reef tank using tap water? YES! For the first 25 or so years of my time in this hobby I used it quite successfully. Were there issues to deal with? Certainly. Late summer the nitrates would increase and so I would develop algae issues. GFO would take care of that for me. I would have seasonal cyanobacteria. Increasing water changes to siphon it out would take care of that. There were other little things as well, but I just considered them to be a part of the "fun".

It really wasn't until I switched to ro/di that I even realized that the tap water could be a contributor to the overall health of the system.

Don't even think, however, that ro/di is a cure-all for whatever water quality issues you might have. Nuisance algae can still be a problem, especially if over feeding or getting lax on water changes and allowing Nitrates to build up in the system. I still keep GFO on hand to use as needed. Cyanobacteria still comes and goes, but not like it used to. IMHO, it is as much an issue of lighting and flow as it is of overall water quality. As fall approaches with the changes in ambient lighting due to the position of the sun in the sky, I fully expect to see a bit of the red scourge once again. It, too, shall pass.

Has the use of ro/di water made my life easier? Sure, but if I had to do without, I know that I most certainly could.

PatW · Aug 10, 2019

We use RODI primarily in two ways. We use it with a salt mix to make up salt water. And we use RODI for top off water for our systems.

Tap water is supposed to just be potable, fit for human use. But corals are more sensitive.

My tap water has .3 ppm phosphates and .5 ppm nitrates. If I used it to mix up saltwater and for top off, I would be plagued with excess nutrients. And it would be an issue I would have to constantly fight. RODI removes that issue.

Also tap water often has copper in it. Humans are not that sensitive to copper but marine invertebrates are. RODI will pretty much prevent you from killing off your inverts with copper. Besides copper, tap water can have levels of other metals like Pb, As and others.

Also tap can potentially have insecticide or herbicide contamination.

Anything in the water can build up in your system over time because of your top off water.

And RODI comes at an expense. But given the price of coral frags, a modest investment in RODI can save you from a coral apocalypse.

Johnnybananas · Aug 10, 2019

Made the mistake of starting my first tank with tap water. Rodi changing everything no more algae and finally got steady parameters

LesPoissons · Aug 10, 2019

you can 100% use rodi for fresh water. my silly fair-won goldfish get the benefit of RODI just like my 220g reef. However, there are no freshwater corals to worry about sensitvity or elevated nutrients. also a lot of FOWLER tanks dont use rodi and are fine. (+/- algae issues). It also depends on your personal tap water how many issues you will have. Most freshwater fish and plants are a lot less sensitive and happy with a de-clorififed tap water and the plants benefit from the phos and nitrates. My goldfish tank has 100x less algae issues using rodi than it did with tap, but the fish themselves had previously lived in a 10 gallon bucket with hose water, no water changes just top offs, no filtration or air stones, and 102 summer heat, full sun, for 6 months and been fine. Saltwater fish dont have that kind of stamina.

Amboss72 · Aug 10, 2019

Billdogg said:
Can you keep a reef tank using tap water? YES! For the first 25 or so years of my time in this hobby I used it quite successfully. Were there issues to deal with? Certainly. Late summer the nitrates would increase and so I would develop algae issues. GFO would take care of that for me. I would have seasonal cyanobacteria. Increasing water changes to siphon it out would take care of that. There were other little things as well, but I just considered them to be a part of the "fun".

It really wasn't until I switched to ro/di that I even realized that the tap water could be a contributor to the overall health of the system.

Don't even think, however, that ro/di is a cure-all for whatever water quality issues you might have. Nuisance algae can still be a problem, especially if over feeding or getting lax on water changes and allowing Nitrates to build up in the system. I still keep GFO on hand to use as needed. Cyanobacteria still comes and goes, but not like it used to. IMHO, it is as much an issue of lighting and flow as it is of overall water quality. As fall approaches with the changes in ambient lighting due to the position of the sun in the sky, I fully expect to see a bit of the red scourge once again. It, too, shall pass.

Has the use of ro/di water made my life easier? Sure, but if I had to do without, I know that I most certainly could.

I too have dealt with the red scourge as the position of the sun changes. Thanks for sharing that! I too began the hobby with tap water. That was back in the days when exotic angels and butterfly fish were commonplace in your local pet store. Back then we didn’t use live rock and the biggest challenge was just getting your exotic fish to eat..

MnFish1 · Aug 10, 2019

Maya Ybry-Yagy said:
you can 100% use rodi for fresh water. my silly fair-won goldfish get the benefit of RODI just like my 220g reef. However, there are no freshwater corals to worry about sensitvity or elevated nutrients. also a lot of FOWLER tanks dont use rodi and are fine. (+/- algae issues). It also depends on your personal tap water how many issues you will have. Most freshwater fish and plants are a lot less sensitive and happy with a de-clorififed tap water and the plants benefit from the phos and nitrates. My goldfish tank has 100x less algae issues using rodi than it did with tap, but the fish themselves had previously lived in a 10 gallon bucket with hose water, no water changes just top offs, no filtration or air stones, and 102 summer heat, full sun, for 6 months and been fine. Saltwater fish dont have that kind of stamina.

It can be a bit dangerous to use 'pure' RODI water in a freshwater tank. Fish require minerals - and there is also some buffering capacity in 'tap water' - that is not present in RODI. If you want to use RODI for freshwater - most people use a mixture with tap water - or add back buffers/minerals - just like you add salt water to RODI. If you only 'top off' evaporation - you shoudl use RODI for both fresh and saltwater to avoid buildup of various chemicals over time

FishyDP · Aug 10, 2019

Chlorine can be added to the above listed contaminates that are removed from tap water by an rodi system..

Dub · Aug 23, 2019

PatW said:
We use RODI primarily in two ways. We use it with a salt mix to make up salt water. And we use RODI for top off water for our systems.

Tap water is supposed to just be potable, fit for human use. But corals are more sensitive.

My tap water has .3 ppm phosphates and .5 ppm nitrates. If I used it to mix up saltwater and for top off, I would be plagued with excess nutrients. And it would be an issue I would have to constantly fight. RODI removes that issue.

Also tap water often has copper in it. Humans are not that sensitive to copper but marine invertebrates are. RODI will pretty much prevent you from killing off your inverts with copper. Besides copper, tap water can have levels of other metals like Pb, As and others.

Also tap can potentially have insecticide or herbicide contamination.

Anything in the water can build up in your system over time because of your top off water.

And RODI comes at an expense. But given the price of coral frags, a modest investment in RODI can save you from a coral apocalypse.

I didn't ask about declorinated tap water. I was asking about RO water. The process is virtually the same as RO/DI. 97-98% of everything is removed from the tap water

Daniel@R2R · Aug 23, 2019

Good discussion! Solid explanations!

K7BMG · Aug 23, 2019

I agree with everything here, and glad to see that FishyDP brought up the number one thing. Chlorine.....

@Dub,
I may have misinterpreted your post so I respectfully apologize and don't mean to offend.

Are you saying Dechlorinated water is the same as RO/DI water?

Dechlorinated water is simply that Dechlorinated only. The retail chemical products used to dechlorinate do nothing for TDS. Yes some will buffer PH but will not remove TDS.

RO/DI systems not only remove Chlorines but most everything else especially the unwanted TDS.

W1ngz · Aug 23, 2019

The serious freshwater planted crowd use RODI as well. They then have often very specific levels and quantities of minerals and fertilizers they add back into their water, and they will obsess about the pH, KH, GH and TDS of their tank water, exactly the way reefers will mix salt and obsess about the salinity, alkalinity and all the fun stuff we do.

There are species of freshwater plants that can be just as demanding and finicky as harder to keep corals.

Dub · Aug 23, 2019

K7BMG said:
I agree with everything here, and glad to see that FishyDP brought up the number one thing. Chlorine.....

@Dub,
I may have misinterpreted your post so I respectfully apologize and don't mean to offend.

Are you saying Dechlorinated water is the same as RO/DI water?

Dechlorinated water is simply that Dechlorinated only. The retail chemical products used to dechlorinate do nothing for TDS. Yes some will buffer PH but will not remove TDS.

RO/DI systems not only remove Chlorines but most everything else especially the unwanted TDS.

Yes I totally agree.. back in the 70's all I did was declorinate tap water. But again all I had in my 75 were fish and invertebrates. RO was around but too expensive as was distilled water and I don't remember any talk of using either, but again - no Internet forums so not much info available. I guess that is one reason this goal of 0 tds originally seamed a little over reach to me. Another reason I view myself as a newby with lots of questions.

Wildblue4 · Aug 23, 2019

I run RODI water. Can I get advice from you guys? My system has 3 canisters then 2 membrane canisters and finally 1 last canister with the TDS meter on it. I make 25 gallons a month for water changes and 15 gallons a week for the ATO.
My question is when do I change out my filters? The first one has turned brown. The second is getting brown. The third is still white. The canister with the TDS meter has some kind of media in it instead of a filter. When should I change that media out? TDS is still reading 1 to 0 on the discharge of the whole unit.
I have just never ran RODI and I don’t have any friends that have any experience with these units. Any advice would be helpful.

Bayareareefer18 · Aug 23, 2019

W1ngz said:
The serious freshwater planted crowd use RODI as well. They then have often very specific levels and quantities of minerals and fertilizers they add back into their water, and they will obsess about the pH, KH, GH and TDS of their tank water, exactly the way reefers will mix salt and obsess about the salinity, alkalinity and all the fun stuff we do.

There are species of freshwater plants that can be just as demanding and finicky as harder to keep corals.

Agreed

The idea is remove all of what you don't want and add back the things you need.

This works in planted tank and also sensitive fish

People that keep wild discus and things like altum angels often use RO, as they do better in softer lower ph water, but trace minerals are also added back in

In our reefs its keeping out all the things in our tanks that we work so hard to minimize such as phosphate, nitrate, metals etc

W1ngz · Aug 23, 2019

Steven Drake said:
I run RODI water. Can I get advice from you guys? My system has 3 canisters then 2 membrane canisters and finally 1 last canister with the TDS meter on it. I make 25 gallons a month for water changes and 15 gallons a week for the ATO.
My question is when do I change out my filters? The first one has turned brown. The second is getting brown. The third is still white. The canister with the TDS meter has some kind of media in it instead of a filter. When should I change that media out? TDS is still reading 1 to 0 on the discharge of the whole unit.
I have just never ran RODI and I don’t have any friends that have any experience with these units. Any advice would be helpful.

Really common question that a lot of people have wondered about. Search will find all the answers you need. If you still need help, I'd suggest starting your own thread, you'll get more specific answers to your specific questions that way.