Rocks from Lake Michigan - The Planted Tank Forum
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post #1 of 6 (permalink) Old 02-18-2014, 01:30 AM Thread Starter
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Rocks from Lake Michigan

So last summer I was at Lake Michigan and while leaving, picked up a couple of rocks. Are these safe to put in my tank? They weren't actually in the water however, if that makes any difference.

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post #2 of 6 (permalink) Old 02-18-2014, 01:54 AM
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I think its vinegar? Or something like that (maybe google or wait for someone else to respond for sure) that you can drip on to the stone to see if it fizzes. If it does, don't put it in your tanks.
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post #3 of 6 (permalink) Old 02-18-2014, 02:11 AM
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Yeah use vinegar to test.


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post #4 of 6 (permalink) Old 02-18-2014, 09:35 AM
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completely unsubstantiated gut feeling type claim... I'd be rather hesitant to put that in a typical soft-water tropical tank.

Aside from that, I've no clue what that rock is. I think the vinegar test is a bit over-rated, as it tends to have a _lot_ of false-negatives (rocks that have high carbonate content, yet don't appear to fizz immediately...), and is also prone to misinterpretation.

If you have easy access to a strong(er) acid, I highly recommend you use that.

Otherwise, I'm partial to the scratch test, I think it's easier, both in interpretation and execution. Take your rock, and see if you can scratch it with the point of a knife, a nail, etc. (pretty much anything made of steel....)

If the rock scratches, it might not be safe (further testing necessary), if the rock does not scratch, it's almost certainly safe.
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post #5 of 6 (permalink) Old 02-18-2014, 03:04 PM
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Put the rock in a bucket of the same water you use in the tank, or in some water removed from the tank for a water change.
Test GH, KH, pH and TDS when you start and every few days for a week or two.
No changes = safe for hard or soft water tanks.
If you see very minor changes then the rock is probably OK as long as you keep up with water changes.
If you see major changes then the rock might be OK in a hard water tank, but not a soft water tank.
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post #6 of 6 (permalink) Old 02-18-2014, 07:23 PM
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+1 for what lochaber said. and that rock looks very much like it's calciferous. The little holes, the whitened edges, the color -- it looks a lot like coral to me, though I don't know if that area used to be seas or not.
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