DO you HAVE to use RO/DI water?

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.

happygirl65

Aquarium Advice Addict
Joined
Aug 30, 2006
Messages
1,358
Location
Flagstaff, AZ
Hello all,
I have nearly been given a green light on my FW to SW conversion of the 46 gal bowfront tank (yeah!)

And I have seen several posts mention the use of RO/DI water exclusively for water changes etc. Is that completely necessary? Or would you recommend it in my case?

I have good mountain spring water collected from underground springs. It is fairly hard water with a pH of about 8.0 and it has been a while since I tested the GH and KH but I think the KH was 7 and the GH 11 last time I checked it.

It is perfectly good water with no chemical additives. My FW fish and planted tanks are all thriving. I know SW is different but how critical is it to have RO/DI water and what would be the major reasons to do so?

Incase it makes a difference the tank will be FOWLR at first with a future upgrade to reef down the road.

Anyone who can shed some light on this water thing will be much appreciated. I just like to understand "why" I guess before I just assume that I need something. :) :n00b:

Thanks a bunch!
 
Because you don't know for sure what else is in your spring water. Most salt brands are formulated to be used with RODI water. If your spring water is already high in calcium, magnesium, or any of the othere 70+ trace elements you may be overloading tank with something. Also, how stable is the spring water? It probablyvaries with the seasons and the amount of rainfall.

Proper testing for human potability can cost hundreds of dollars. When was the last time this water was tested?

Do you have to use RODI? No. Should you? YES!
 
Many problems that accure in a SW aquarium take time , months or yrs , to appear , after youve spent lots of money and used lots of time , and can be much harder to fix leaving many to give up from frustration or tank crash.

You cant test small batches and get long term results as many problems collect little by little. Problems from the source or pipes bringing the source.

For the best chance you want as much controll as possible , and the water source is a large control factor.

You might get by with a startup but i would get a RO/DI unit A.S.A.P.

Get a book you wont regrete it.
 
All tap water is different but you just never know for sure. For the sake of consistency, I would still suggest using RO/DI water. For the long-term it is simply the safest.
 
Well, our water has never been tested. We have lived here for 6 years (built the system and the entire place ourselves) so there is nothing in the pipes that would be a problem. The springs are created from snow melt as we are in the mountains. But clearly there are loads of minerals in it or it wouldn't be so hard.

I am starting to understand the point of view. Especially since the commercially available salts add the trace elements that my water most likely has already. I did not know that. So I am always glad to learn something new. :)
 
I would also suggest a RO/DI unit. Alot of your spring water contains fertilizers from rain runoffs. Err to the side of safe.
 
Do you mean naturally occuring fertilizers as in trace elements? If so ...agreed.

I often do wonder what is in our water but we are way up in the mountains in a remote area...there is no farming around or above us as we are in the midst of a true mountain forest and it surrounds us on all sides.

I grew up in the city (Phoenix AZ area) and we never trusted our water....and when we first moved to western MT I had a lot of issues with what "could be" in there and it took a long time for me to trust it but my husband grew up here drinking the water and he and all of his brothers are so healthy and strong so I began to trust it.

But it's always there in the back of my mind and the last thing I would want is for this issue to ruin my efforts at a brand new hobby. Especially when it is not that hard or expensive to put in the filter.

Also the pH does fluctuate with the rainy season vs. the dry season so that point is well seen.

I know that my water must have loads of elements in it because my planted tanks are high tech and I rarely need to add anything except for potassium and if I do then I get algae.
 
You are starting to see the light. Our SW tanks cost a small forutne when everything is taken into account (inlcuding our blood sweat and tears). Why take a chance on the most important thing in our tank, the water? A RODI unit is small price for the peace of mind it brings.
 
I often do wonder what is in our water but we are way up in the mountains in a remote area...there is no farming around or above us as we are in the midst of a true mountain forest and it surrounds us on all sides....

You'd be surprised how far aquifers can "pull" their water from. Western Montana has it's share of nasty mining areas that pumped a fair amount of stuff into the ground, if I remember correctly. Not saying that your water isn't pure, but as folks have pointed out... you just don't know - unless you get a full series of water tests from a commercial lab. (And that only tests the water for that instant in time. Could be different next week!) As your tank gets older and has more $$ invested in livestock, the cost of running a filtration system is really peanuts when you think about it.
 
You'd be surprised how far aquifers can "pull" their water from. Western Montana has it's share of nasty mining areas that pumped a fair amount of stuff into the ground, if I remember correctly. Not saying that your water isn't pure, but as folks have pointed out... you just don't know - unless you get a full series of water tests from a commercial lab. (And that only tests the water for that instant in time. Could be different next week!) As your tank gets older and has more $$ invested in livestock, the cost of running a filtration system is really peanuts when you think about it.

I am definitely seeing the light. :) I hadn't thought about the mining....very good point. There were two of thm not to far from us (gold mines) and up country from us as well. They have not been active in close to 100 years but you just never know. :) I have seen the environmental impact in some neighboring counties of the active mining so that is actually a bit scary thinking about that. I know nature heals itself and nature has reclaimed those upper mines (I have been there exploring recently) but who knows what leached into the soil and/or ran downstream from all of that.

I am living in "Mineral County" afterall and who knows there may even be trace elements of copper and I certainly wouldn't want that. I am glad that my husband is open to getting the filter anyway. That takes a huge load off.....

If you all could help me clarify though....and perhaps this is a dumb question but I have to justify my position with my husband....What is the difference or rather the impact on a SW system with RO vs. RO/DI water.

I know you mentioned getting one that can do both which sounds ideal but I need to be able to explain exactly why I need the DI part of it....if you you all could help me out with that one. :)

Oh, and thnk you so much! I really appreciate all of your help. If it wasn't for AA and you fine folks I would not have the courage to try this...so really...from the deepest part of my heart...thank you!:-D
 
The difference between RO and RO/DI is just purity.

RO gets out between 95 and 99% (roughly) of the impurities. There are still some in there after it passes through the RO membrane.

The DI stage gets out that last few percentage points and gives you as close to pure water as you can get.

There isn't a lot of cost differential between RO and RO/DI units, and the DI stage doesn't effect anything except for the extra $10-20 a year you need to spend to replace the resin.
 
Thanks so much guys! The article was awesome thank you! It said in detail what Kurt summed up nicely. And my water does have 1ppm phosphate which is fine for the planted tank but not so much for SW according to everything I have been reading. So I will definitely want to remove that.

SO I will begin my exhaustive search for the best RO/DO filter that $200 can buy...lol.

Thanks again...you folks are awesome! :)
 
And my water does have 1ppm phosphate which is fine for the planted tank but not so much for SW according to everything I have been reading.

You got that right! Everything I've read says anything over 0.03ppm is too much for coral. But I think that might have more to do with the lowest resolution of our test kits.
 
FWIW, AirWaterIce recommends a 10 micron sediment filter followed by a 5 micron charcoal, followed by a 1 micron charcoal before the RO membrane. That helps the membrane last longer.
 
Awesome...thanks! That seems like a great price. Also we have a sediment filter that we have used in the line. I am sure we can hook that up before the water goes into the unit to filter out the big chunks. :)
 
Back
Top Bottom