Reconstituting RO water

[Neil]

I thought that I would start a new thread here because this is an interesting topic and was being discussed in a thread that was probably not what the original poster wanted to know.

kribs wrote:

HI
It is pure RO i have not even mixed any peat or anything like that but the gravel in the tank came from an already established tank and the fish were living in it before and i have various different apistos in it and they are all fine. IT doesnt look like a scrape though.
thank you

Bissot_J wrote:

Pure RO ?

i have a question about that .....
is Pure RO is good for life..... ?
i always read/heard/understand that Pure RO doesn't contain (or not enough) vital elements.... so what is the opinion of forum members on that ?

regards

farm41 wrote:

That's what I have heard, you have to mix some tap back in, or reconstitute with a some man made products.

In actuality (depending on the age of the RO membrane) the water prduced by a unit is not pure. Close. The second the water comes into contact with any other materials (gravel, plants, rocks, filter and especially food) it decreases its purity even further. I don't know for sure but the elements leeched from these materials are sufficient to sustain any soft water fish. As a matter of fact, I have put apsitos in a new tank with 100% RO so many times that I can't count them all. Just look at the conductivity of pure RO! Many of the biotopes that our fish come from are very acidic, and virtually no harness with minimal conductivity and/or TDS. If you are adding tap water back into RO "pure" water just because you think the fish cannot live without it, you are just placing some of the material that you spent the time and money to get rid of back into it. However, if you are putting some tap back in to buffer the water so that a particular pH can be maintained, that is a different story.
Di is a different story. As far as I know DI is truely pure and will probably have an affect on the fishes ability to regulate the water. But someone with more knowledge than I should address these specifics.
Neil

 

[farm41]

OK, so do I need to add anything to water for my rams?

I have been adding 50% tap because I am buying from a friend and hauling it home in 55g barrels. I have ordered a 60 gpd RO unit and I could use straight RO if needed.

Are you keeping any fish in straight RO water?

 

[tjudy]

I have a little book written by Dr. Rolf Geisler back in 1963 (published by TFH) titled Aquarium Water Chemistry. Cool book. Not as out of date as you would think.

Here is a formula from the book that can be used to reconstitute RO water accurately (all numbers are ppm):

1) List the tap water hardness above the RO hardness:

300


0

2) Place the desired hardness between and to the right

300

50

0

3) Calculate the differences in the diagonals (300-50 = 250, etc.)

300 50

50

0 250

The differences show the relative amounts of water to be used to reach the desired TDS. The upper number (50 in this example) is the tap water, and the lower number is the RO water. Therefore the ratio is 250:50 RO:Tap. That can be reduced to 5:1.

If you wanted 6 gallons of 50ppm water using the above example, you would mix 5 gallons of RO with 1 gallon of tap.

To figure that out for any volume, divide the volume by the sum of the numbers in the ratio 5:1. (5 + 1 = 6). A 120 gallon tank, divided by 6, equals 20 gallons. To use the ratio for that volume of water (120 gallons), you would use 20 gallons x 5 = 100 gallons of RO; and 20 gallons x 1 = 20 gallons of tap.

So long as you know the TDS of the water you are going to use to reconstitute the RO with, this calculation will always work.

 

[Orchid]

I like that water mixture plan, tjudy. That would make mixing to the right pH a whole lot easier.

I use straight RO in my tanks if I am just topping off which can often be as much as seven gallons in my 55 gal discus tank. RO water is "considered" pure, but as soon as it comes into contact with water that is less pure, then it strips the impurities already in the water and becomes less pure itself. This happens very fast. My fish often swim through the new water flow and I've yet to have anything go wrong (knock on wood).
Straight RO would be fine to use in 10%-20% water changes and fill ups.
I've read many accounts were people keep apistos in straight RO.

Distilled water is a different story. This water has been completely stripped and is very hungry for ions, it is a very effective acid. I used to work in a metals lab where we tested soil and water samples for different metals. The companies that we tested for answered to the EPA, so our data had to be accurate. We used distilled water to clean our glassware so that no impurities would be left to contaminate future tests.

Even though distilled water would also become less pure once it came into contact with tank water, it is so stripped it would still harm the living skin of fish. The labels on bottled distilled water says DO NOT DRINK, because it will do the same thing to your throat! Definately reconstitute distilled water if you use that.

 

[Neil]

Are you keeping any fish in straight RO water?

Yes, but it is cycled by a foam filter that is seeded from another tank. I usually put a little water (from a mature tank) in as well. As is been said in this thread already, RO water doesn't stay quite as pure as it is when it first comes out of the unit once it has been exposed to anything. I don't fill up a brand new tank with pure RO water (and with a new unseeded filter) then dump my fish in there. However, I suspect that they would swim around happily until the cycle started if I did. As Orchid said, there is a large difference between RO and DI.

OK, so do I need to add anything to water for my rams?

Yes you need to add whatever it will take to maintain the pH at the level that you want. Additionally, for growing fish, mineral may be very helpful for their development. Tap water has stuff that may not be. You can add any number of things to reconstitute the water with all of the elements that you want and none that you don't. The above example of putting fish in basically pure RO is for tough-to-breed fish that may have fry that require very pure (soft) water to effectively spawn viable fry.
Neil

 

[Bissot_J]

I thought that I would start a new thread here because this is an interesting topic and was being discussed in a thread that was probably not what the original poster wanted to know.

Good

In actuality (depending on the age of the RO membrane) the water prduced by a unit is not pure. Close.

Totally agree

The second the water comes into contact with any other materials (gravel, plants, rocks, filter and especially food) it decreases its purity even further. I don't know for sure but the elements leeched from these materials are sufficient to sustain any soft water fish. As a matter of fact, I have put apsitos in a new tank with 100% RO so many times that I can't count them all. Just look at the conductivity of pure RO! Many of the biotopes that our fish come from are very acidic, and virtually no harness with minimal conductivity and/or TDS. If you are adding tap water back into RO "pure" water just because you think the fish cannot live without it, you are just placing some of the material that you spent the time and money to get rid of back into it. However, if you are putting some tap back in to buffer the water so that a particular pH can be maintained, that is a different story.

rigth.
So can we say , it is safe to start a new tank with some water of a existing tank and the rest with RO Pure ?
and usually me i dont mix tap with RO water, i just add some "electro rigth" or "Ro-Rigth" who supposed have the element need, and who help to get the Param you try reach

Regards

 

[Roger]

I use RO water for my wild discus since I keep their pH and water close to what nature started them out with. My water is rock hard and has a high ph to boot.

I would want to think that your adult fish could care less about the water until it comes down to breeding time. Your juvi fish on the other hand probably wont do well in pure RO because of the lack of minerals in the water.

The person that I bought my wild discus from recommended using sea salt ie Instant Ocean aquarium salt, to add minerals back into the water. I think the formula was 1 tblsp tp 55gal.

Peace,
Roger