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Re: Rocks in Planted Tank

Granite is quite inert, and usually will have no effect on the water. It is
mostly SiO2 and equally insoluble compounds. Good choice, IMHO.

Limestone, marble, dolomite, etc., will raise your GH and KH, but in
semi-uncontrolled ways. They dissolve faster in acid conditions, so the
water will be constantly changing, but not always at the same rate. If your
starting water is hard and alkaline, they may have little effect. If it is
soft, they may have wildly varying effect.

Water changes would need to be small and frequent, to avoid osmotic shock on
the fish. As time goes by, the soluble materials seem to "skin over" and
become less soluble, unless shocked by extra acid conditions.
Unpredictability is the only predictable consequence. ;-)

I test suspicious stones with pool acid, to see if they contain solubles
like CaCO3 o/e. If the rock shows any "fizzing," I reserve it for hard-water
or brackish tanks or (most often) discard it.


> Date: Sat, 02 Feb 2002 23:11:00 -0800
> From: Ed Dumas <a4a48835 at telus_net>
> Subject: Rocks in Planted Tank
> I want to add some rocks to my planted tank just for the purpose of
> landscaping. I already have some lava rock, and I was hoping to use some
> other kind of stone. I would like to know if anyone has knowledge about
> what is suitable for plants and fish. I understand that granite is a
> no-no because of its limestone base. Is that correct? How is granite in
> plant/fish tanks?
> Ed Dumas

Wright Huntley -- 650 843-1240 -- 866 Clara Dr. Palo Alto CA 94303 

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