# How to test and clean rocks for a cichlids aquarium?



## vicd1234 (Oct 15, 2014)

I just picked up a bunch of black river stones and other rocks from a river by my house for use in my aquarium.
How do I know if it's safe to use in my cichlids tank? I was told to use vinegar to drop on a rock and see if it fizzes. However I was told that if it did fizz this meant that it would likely raise my pH, not make it useless altogether. So I am just curious what causes it to fizz and why does this make it a rock you would not put in your tank? Can I use them in cichlids tank?
Thanks :-? :-?


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## notho2000 (Dec 8, 2012)

The vinegar test (or any acid for that matter) will react with limestone (calcium carbonate) to produce carbon dioxide (the 'fizz'). Throughout Central America and Mexico, this is the predominant substrate and rock and it will generally produce increased hardness and pH. This is also the case in Lake Malawi and Tanganyika. So if you keep these types of fish, no problem. The only time limestone should be avoided is for South American cichlids which require softer, more acidic (pH<7) water. The black stones you collected are most likely basalt, produced from rapid cooling of lava. They are inert (i.e. it will not alter pH and hardness) and hence totally safe to use.
As far as cleaning them goes, I just use a stiff bristle brush (no chemicals) on the surface. You can scrub with salt/water as well. Another approach is to immerse the rocks in a weak bleach solution for a few hours, then rinse well. Then immerse them in water to which a declorinator has been added, leaving them overnight. Then rinse well and use. Some declorinators are sodium thiosulfate (cheapest), sodium hydroxymethanesulfonate (used in AmQuel), and sodium hydroxymethane sulfinic acid (used in Marineland Bio-safe).


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## vicd1234 (Oct 15, 2014)

Thank you so much for your response. Great info.


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## The Cichlid Guy (Oct 18, 2014)

I found that a pressure washer can be very helpful when scrubbing just isn't enough. The "black" rocks I found in my local river turned out to be gray, red, and brown.


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