# What rocks are safe to use?



## pupfish (Jul 25, 2006)

I'm wondering specifically if a nice peice of granite I have would be safe. Namely I'm looking for light-colored rocks and this one goes with the gravel I'm going to use as a top layer better than anything else. I've also considered trekking to the local rock shop for some chunks of white or peach quartz, but this granite is just the perfect shape; a narrow upright, and looks to be about 2/3 little chunks of white quartz in a slightly darker rock. Anyway, I've heard mutterings about not using rocks if you don't know what's in them, but I don't know what's in any of them except that quartz should be hard and inert, so what about granite?


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## Ajax (Apr 3, 2006)

I've never heard of any granite not being safe, so I think you would be ok. I would scrub it with a bleach solution and then rinse it real good. Maybe let it soak for a little while in straight water.

The main concern with rocks is calcium content which can play havoc with your GH levels. The way to test this is using muriatic acid. Pour some on the rock, if it bubbles it has calcium in it.


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## CherylR (Aug 12, 2004)

Anything I soak in bleach, I always soak in dechlorinated water with plenty of extra dechlor for a few minutes after I'm done cleaning it. If it's something porous like driftwood I soak it overnight.

The worst thing that will happen if you use an inappropriate rock is that your GH or KH will climb as the rock leaches minerals out of the water. The more acidic your water, the faster the rock will leach minerals. None of this will hurt the fish.

Muriatic acid will certainly do the trick, but be careful handling it. It is very strong and you don't want to spill it on yourself.

Another way to test a rock is to soak it in a bucket for a week. Test the water after a week. Is the GH or KH any higher? Then maybe you don't want to use it. Or maybe it's not so bad that you care.


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## Sudi (Feb 3, 2005)

Hmmm... How about Vinegar? 
Everyone has that at home, just pour some on the rock and if it doesn't bubble it's good for aquarium 

Muriatic (aka. Hydrochloric) acid can be harmful, so I personally wouldn't use it if there are children around. Vinegar is less concentrated but also does the job.

Matt


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## trenac (Jul 16, 2004)

Safe rocks

_1) Are hard & well weatherd_

_2) Stay completely unchanged in water_

Unsafe rocks

_1) Containing carbonate minerals_

_2) Intricately shaped rocks_ (sometimes)

***You can test for carbonate minerals by using vinager (safer method/sometimes not strong enough) or muriatic acid (can be unsafe if not used properly).


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## Clone (Mar 9, 2005)

If you are sure it's granite then dust it off and drop it in. No need to test it for carbonates.


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## Rich M (Mar 6, 2004)

When testing with vinegar it's best to scratch the rock with a metal object like a nail (in an unseen area such as the bottom) and pour the vinegar on the scratch. The bubbling will be more obvious this way.


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