# Rain water



## adam79 (Jun 27, 2007)

I have heard of people useing rain water in their tanks. Does rainwater have the same properties as as R/O water? What precautions should be taken when using rain water?


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## bluedog800 (Aug 26, 2010)

i to have heard of this with people that are keeping brackish water tanks... to my understanding you don't have to do much with it, i would add a bubbler to it and perhaps a goldfish if it is outside to keep the insect's out...


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## Number6 (Mar 13, 2003)

rain water is not like R/O water... R/O water is basically "just" H2O. Rain water is H2O and whatever it scooped out of the air on the way down. Dust, metal, acid... you name it.

Rain water is nice and soft water, like R/O so it would have that in common. I used to filter rain water through a solid carbon block filter and then use it on black water cichlids... ebay R/O filters made that an obsolete activity thank goodness.


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## adam79 (Jun 27, 2007)

I was aware of pollutants. The air here in Idaho is some of the cleanest in the country. Other than potential pollutants, rain water is basically the same outcome you would get from a R/O filter, Right?


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## Number6 (Mar 13, 2003)

IME, rain water had a TDS reading of 60ppm, where my R/O filtration system had a TDS reading of 1ppm. Tap water had a TDS of 480ppm... So, rain water doesn't have as much stuff in it as tap, but more than R/O water. I don't think I'd ever say that the water is anything like R/O water... one is dirty, the other is super clean.

If what you mean though is about the softness of the water, then yes... rain water should have a GH and KH of zero like R/O water.

I'm hoping I've answered your question... I'm not sure I understand your question, so I gave you as much info as I could in the hopes you can then fill in the blank. :thumb: Let me know if you're set.


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## adam79 (Jun 27, 2007)

That was the info. I was looking for. Thanks! :thumb:


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## Chromedome52 (Jul 25, 2009)

Rainwater is also not like R/O in that the quality of it depends a lot on where you live. I suspect the rain in low population Idaho would be much less polluted than in heavily populated Florida. Here on the shore of Lake Michigan, the rainwater tends to be quite acid due to Chicago and Michigan City, Indiana, being upwind of us. However, The hardness was only around 15ppm. I simply used peat as a filter, and bred a great many softwater fish using rainwater. R/O does make it much easier these days.


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## CoolCichlid (Feb 12, 2010)

Number6 said:


> rain water is not like R/O water... R/O water is basically "just" H2O. Rain water is H2O and whatever it scooped out of the air on the way down. Dust, metal, acid... you name it.
> 
> Rain water is nice and soft water, like R/O so it would have that in common. I used to filter rain water through a solid carbon block filter and then use it on black water cichlids... ebay R/O filters made that an obsolete activity thank goodness.


You mentioned about blackwater cichlid, what are they?


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## PsYcHoTiC_MaDmAn (Dec 26, 2005)

CoolCichlid said:


> Number6 said:
> 
> 
> > rain water is not like R/O water... R/O water is basically "just" H2O. Rain water is H2O and whatever it scooped out of the air on the way down. Dust, metal, acid... you name it.
> ...


their cichlids that come from blackwater rivers.........

blackwater refers the staining of the water by tannins, for example rio *****, this photo shows it meeting main muddy waters of the Amazon









stolen photo from the web, but a nice blackwater setup with discus


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## naegling23 (Jan 4, 2008)

Rainwater can work, but there are a lot of concerns. I would always worry about pollution that the rain collects on the way down, but you suggest that that would not be a problem. A lot of cheap plastic buckets and containers may leach various chemicals out of them, especially when exposed to the heat of the summer, so you would have to make sure you get food grade containers. Also, dont collect it from the roof/gutters....I dont even want to think about the **** that comes off my roof, but it certainly wouldnt be good for the fish. So, if your collecting rainwater your going to need some sort of giant cistern in your yard....which, in about 3 days will make you the local mosquito farmer...although you could mesh the top, or add mosquito fish to control them.

Basically, as others have mentioned...yup, you technically can use rain water...but you can get a 75gpd RO filter for like $100...its easier, more reliable, and safer.


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## Pali (Dec 22, 2009)

Number6 said:


> IME, rain water had a TDS reading of 60ppm, where my R/O filtration system had a TDS reading of 1ppm. Tap water had a TDS of 480ppm... So, rain water doesn't have as much stuff in it as tap, but more than R/O water. I don't think I'd ever say that the water is anything like R/O water... one is dirty, the other is super clean.
> 
> If what you mean though is about the softness of the water, then yes... rain water should have a GH and KH of zero like R/O water.
> 
> I'm hoping I've answered your question... I'm not sure I understand your question, so I gave you as much info as I could in the hopes you can then fill in the blank. :thumb: Let me know if you're set.


Rainwater deffently have a smaller ppm then tab water forshure, but there is no controll with what the 60 ppm is.

The 480 ppm in your tab water you know what is, well if you call your water suplyer they can list all the additives they add to the tab water.

Rainwater can be a great source of water to your tanks, but then again other places it's not really a good option as there can be polutions in the air. That could build-up in the tank or even kill your fish at much lower levels.

Pesdicides and many other really harmfull chemicals, can be airborn and absorbed by rain on the way down. Thats what you really need to be monitoring, the pH and most metals are not gonna harm the fish in 60 ppm solutions or less. As there i little to no chance taht all 60 ppm is one chemical alone, it will be a mix of several different chems.

So if you know there is citrus/orange plantages ect. ect. or in the middle of a million ppl city or very close too, rainwater can be a very very bad choice. I would deffently send it in for a lab test to see whats in the water in general.


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