# Concrete in Aquarium?



## metrov (Oct 16, 2008)

Hi,

Does anyone know the pros and cons of using concrete in an aquarium? I have a 100 gallon, fresh water tank with a couple of large decorative objects inside made of concrete -- a Buddha head, and an Angel.

My water always tests very high alkalinity. I keep trying to lower it with PH adjusters, and it won't budge. I'm beginning to wonder if it's from the concrete objects? Also, it seems a lot of my fish die for no apparent reason, because the water otherwise tests fine.

Thanks


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## Chrisseh (Aug 24, 2008)

I don't know about concrete, but typically we don't use objects that are not sold for aquariums because of the paint. If they are painted peices then the paint might be leaking into the water or worse, the fish are eating it. What's the rest of your tank parameters?


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## iamntbatman (Jan 3, 2008)

As Chrisseh said, the paint could be toxic. I'm not sure about the chemical makeup of concrete, so there might be something toxic in it as well. It does have limestone or something similar in it, so that's probably keeping your pH high and making your water very hard.


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## Tyyrlym (Jun 1, 2008)

Depending on what the concrete was made of, yes not all concrete is created equal, it could very easily be the source of your high pH.


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## Oldman47 (Sep 7, 2007)

One of the ingredients in making good strong concrete is lime. Needless to say, lime leaching into the water will raise the hardness and the pH of your water.


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## xyph (Oct 25, 2008)

I know that my family in rural Texas keeps goldfish in outside concrete ponds. They tell my that a new concrete container must sit in water which is occasionally circulated for a couple of years or the fish will die off. Don't know the chemical specifics, but I have refrained from using it as I don't want to bother to 'cure' it for so long.

Btw, first post, Hello


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