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I took a trip to a a lake this weekend, where there was tons of rock. several park rangers told me the rock all around the bluffs were quartzite. I was wondering if this is the same as quartz, and if it is aquarium safe. I know about the vinegar test, but I dont have any vinegar on hand right now and it could save me a trip to the store if anyone knows

The vinegar test isn't the best. It detects large amounts of carbonates basically, which take the form of MgCO3 and CaCO3 (magnesium and calcium respectively). The better method is to take a rock and set it in a bucket for a week or two. Measure the pH at the beginning of the week and the end. Another method is to just know what the rock is. Quartzite is fine. Its made up of quartz. Just make sure its not sooty or blackened from pollution. Don't collect it from polluted places. For example, collecting downstream from a paper mill is a bad idea. Collecting near a highway would not be good either.

Testing the pH as described above is still advisable.

If you have a nitrate test handy, check the ingredients of the reagents. On my test, one of the bottles contains hypochloric acid and that will perform a "vinegar" test quite nicely. But I'd second Hazy's suggestion that a week long soak followed by a pH test is a good plan.

Hi,
Any variety of Quartz is fine in a tank. Its actually
almost the same chemical makeup as the glass of your
tank, SiO2 but with an occasional impurity and those
impurities color the quartz and are bound so tightly
that they will not interfer with the tanks water.

Field Geologists generally carry a small bottle of
dilute Hydrochloric Acid (HCl) with them and if in
doubt about a rock, will strike it to get a fresh,
unweathered surface, and drip a drop or two of
the HCl on it. If it bubbles, then we say it is
a Carbonate. Most folks don't have that available,
and in many cases children have the tanks and are
interested in the rocks. The most commonly available
"acid" in the home is vinegar, and most carbonate
rocks, with fresh surfaces, or powdered, will react
with the vinegar. Others are more tightly, chemically
bound, and it takes a stronger acid to cause the
fizzing reaction. For those, placing the rock in
water of a known pH, and then testing a week later,
could indicate a carbonate. However, a changing
pH is also normal in a bucket of water left to
stand, and one should not confuse the normal shift
of pH with a reactive rock.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

I was wondering, on the subject of rocks, how big a rock to put in my 37 gallon tank. I am starting a lake malawi cichlid tank and have found limestone rocks on e-bay that look pretty cool. They are holey and are said to be pressureblasted and disinfected (i.e., treated to go into a tank). Question. What size should I get? They have anywhere from 5 to 15 pound rocks. Thanks for your help.

Hi,
As far as how much/many rocks are concerned, I would take
a page from the salt water folks as they set up reef tanks
with "live rock" from the ocean. They build walls of the
stuff in the tanks with no damage at all.

Two things to be sure of.... First, set the rocks on
the glass bottom, or use a piece of "egg crate" (the
stuff you see in flourscent lights with 1/2 inch plastic
squares). The egg crate gives you a supporting surface
that won't crack or scratch the glass. By setting the
rock directly on the glass or egg crate, you have a
firm surface so the rock is stable. If you set the
rock on a layer of gravel, as the fish rearrange the
gravel the rock can become unstable and tumble over
striking other glass surfaces and cracking or even
breaking them.

Second, remember, as you add rock, you displace water.
Alot of rock, and suddenly that 30 gallon tank is
holding far less water and that means that you have
to not put as many fish in the tank as it would
easily become over stocked.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Hello... i have a question.
I was wondering about rocks,stones..should i buy the crystal aquarium stones..or could i use some stones i found at the beach..and if i can use them how shall i clean them..leave the stones in freshwater for some days?

---

I know human beings and fish can co-exist peacefully.

Hi,
Yes, you can collect rocks for the tank from your beach.
However, think before you do it. Is polution a problem
with the water? Also, various forms of algae, and
"critters" will be living on the rock and in any cracks.

You will have to clean the rocks (give them a really good
scrubbing) and then kill off anything that might be living
on or in the rock (boiling for several minutes would do
that).

Lastly, assuming that this is not a tank for Rift Fish,
you need to be sure that the rock will not affect the
your tanks water (pH, GH, KH). To do that you would
scratch the surface of the rock to get a fresh surface,
and dribble a drop or two of regular vinegar on the
scratch, and see if it fizzes. If it does, then I
would not use it in your freshwater tank as it is
what is called a Carbonate, and can over time affect
your water, making it hard.

Hope this helps...
Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Thanks frank,
you've helped me alot too