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Newbie question about stone

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Hey Planted tank, I'm new here as you can tell i joined recently.
A friend of mine "Akythara" has some how gotten me interested in planted tanks and with my other passions being history. I plan to create a Greek or maybe Minoan temple.
Unfortunately i do not have the foggiest idea of what would raise/lower the PH, be harmful to plants and fish.

So could someone help me?

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4,112 Posts
A good thing to try out is use a dilute hydrochloric acid solution and apply it onto the rock or rocks in question. If it starts to sizzle/bubble, than it will affect your pH. I prefer using those that are completely inert like lava rocks. Vinegar can be used but a stronger acid like hydrochloric or muriatic acid found at some home improvement stores are better and will show better results.

Some good ones are slate, lava/volcanic rocks, granite, basalt, syenites, diorites, gabbro.

Avoid limestone and marble unless you dont mind the gh and kh shifts and a few other things. Test it using the acid test.

Just look at some of the rocks, but beware that some bottom dwelling fish may hurt themselves on rocks that have pointy edges. Plecos are a good example. Test all rocks, even the ones that are considered safe.

379 Posts
Most rocks and stone are fine for fish. The only one that really can cause problems is limestone and maybe marble because it dissolves and releases carbonates/bicarbonates into the water raising the pH. This is only a problem if you are trying to keep soft water, low pH conditions. If you are keeping african cichlids or something that likes higher pH, limestone is fine.

To test any potential rocks, you can drip vinegar on them, if it fizzes, it has limestone in it. The other thing you can do is place the rock in water for a few days and see what happens to the pH.

Like I said though, most rocks are pretty inert, especially the dark colored ones.
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