# Distilled water vs RO water?



## Hilde (May 19, 2008)

Read that for people there is little difference between using RO water and distilled water. 

Is this the same for planted tanks?


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## bsmith (Jan 8, 2007)

Distilled is when the water is turned to steam and then collected, RO is when the water is forced through a membrane for purification.

Wikipedia


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## Hilde (May 19, 2008)

bsmith782 said:


> Distilled is when the water is turned to steam and then collected, RO is when the water is forced through a membrane for purification.
> 
> Wikipedia


I already googled it and found that info. Looking for info about affects on fish and plants in aquarium.


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## bsmith (Jan 8, 2007)

I have always used RO water but that may be overkill. If distillation is good enough for my spirits why not my fish!


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## wkndracer (Mar 14, 2009)

Distilled is even cleaner than R O. BOTH have to have mineral traces restored to make it suitable for fish and plants. Cost to produce is the primary factor.

Drinking nothing but distilled can lead to health problems. Besides it tastes like,,,,,,,,,,NOTHING.

Used nothing but distilled for two planted tanks for nearly a year no problems using GH booster.


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## KevinC (May 24, 2004)

wkndracer said:


> Distilled is even cleaner than R O.


I'd venture that RO/DI is more pure. Distilled removes the nonvolatile things (like salts) but not volatile organics. RO has a carbon cartridge to remove organics plus the membrane for most ions, then add DI and you've got them all.

Effect of either on fish: you won't be able to tell the difference. As stated, use GH booster to add the correct minerals back to the water and/or mix with your tap to get the appropriate levels. I'm firmly on the side of not fighting with my tap water - I use it as-is.

I've seen a quote from my DNR that water with high hardness and alkalinity is more productive in terms of plant life.


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## wkndracer (Mar 14, 2009)

Most all commercial distillation processes are more than simply heating to steam and capture of the product. 
Also DI final stage filtration is not recommended by most R O vendors for tank use as the resin beds are expensive to change when exhausted and an unnecessary step for fresh water tanks. At least those were the responses from several that gave me quotes on a system. 
Not messing with your water is wonderful if you have that option:thumbsup: Some of us don't. My well water for example earned me the nickname Fishkiller at the LFS before going first to distilled then R O.

I honestly don't know, but will ask, Why is distilled water recommended for topping off lead acid batteries and R O not?


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## Hilde (May 19, 2008)

Very interesting info! :thumbsup:

I believe best to try to not adjust parameters too , for when I did loss a few fish. 

I was reading a thread where people talk about using RO water to soften the water. I have not seen RO in the grocery store, thus I was curious as to if if distilled water could be used instead of it.

I just love to gather info to help others.


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## bannh (May 3, 2008)

Molecules smaller than water and dissolved gasses can pass through the RO membrane. What gets past the RO membrane can only be removed by DI resin *if* it has an ionic charge, not everything does.

Both the RO membrane and DI resin can have bacterial growth which ends up in the end product water.

Distilled water is much more pure and is also sterile.


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## mistergreen (Dec 9, 2006)

distilled - > condensations of H2O molecules
as pure as you're going to get.

That's why we use it to make drop check solution... ph = 7, (KH,GH) = 0;


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## KevinC (May 24, 2004)

mistergreen said:


> distilled - > condensations of H2O molecules
> as pure as you're going to get.
> 
> That's why we use it to make drop check solution... ph = 7, (KH,GH) = 0;


Not at all. pH = 5, kH and GH = 0. Since CO2 is in the air, it dissolves in the distilled water as it is made (and while stored), forming carbonic acid and reducing the pH.

Adding a little bicarbonate to make a drop checker solution overcomes the dissolved CO2, giving a buffer (KH = 4 or 5).

Additionally, if the feed water has small organic molecules (with low boiling points), these will distill over with the water and stay in it. For example, methanol and ethanol (from fermentation processes) would remain in the distilled water.

Then add the fact that most distilled water is produced off-site then stored in a plastic bottle on a shelf for a while and you can see how other organics might end up in it. It is also possible to be non-sterile depending on the conditions at the bottler.

Still, either one would be fine (if brought back up a little in kH and GH) for your plants and fish.


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## Wö£fëñxXx (Dec 2, 2003)

Apples and oranges, either one is fine if tap water is polluted or
if you just want water that is lower in TDS for specific fish/plants.


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