View Full Version : Aquarium safe rock

08-26-2008, 4:19 PM
What kind of rocks are safe for an aquarium?

08-26-2008, 4:21 PM
This is from a sticky on guppies.com:

Distilled white vinegar can be used to determine if a rock is safe. put a few drops on the rock, wait a couple of seconds and watch for bubbles. If bubbles are seen, this rock is NOT safe.

One point to remember is some rocks are made up of a conglomerate of differing minerals and smaller rocks. It would be a good idea to test each rock in numerous places. This test can also be used to verify you choice of substrate for compatibility.

Below is a list of rocks that are safe for aquarium use.

Safe Rocks:

* Crystalline Quartz
(Rock Crystal, Amethyst, Citrine, Rose Quartz, Smokey Quartz)
* Granite
* Jade
* Lava Rock
* Microcrystalline Quartz
(Jasper, Agate, Chalcedony, Sard, Carnelian)
* Onyx
* Petrified Wood
* Quartz
* Slate

Unsafe Rocks:

* Coal
(Commercially harvested coal is treated with an oil by-product to reduce dust)
* Coral
* Dolomite
* Fools Gold
(or any other rock with metallic veins--Acid Producing)
* Fossils
* Marble
* Limestone
* Sandstone

Keep in mind that some of these rocks can be used in some tanks. Crushed Coral makes an excellent substrate for maintaining water quality for African Cichlids. You can even use some rocks that come from limestone to do the same. Limestone will usually do nothing more than raise your water parameters. If you decide to use rocks that will contribute to the overall hardness, make sure you test the water parameters to get a handle on just how high your levels will increase over time.

08-26-2008, 4:26 PM
Not Flagstone! As I have recently discovered - raised my ph way up!

Alan R
08-26-2008, 4:26 PM
Granite :)

08-26-2008, 4:28 PM
they have most of those at a material depot?? And would they let me dig through the little pile???

08-26-2008, 4:35 PM
They should have at least the granite and slate, probably quartz and lava rock too. Hard to say about the others. As far as them letting you dig around, I have no idea. Wouldn't hurt to ask anyways. :)

08-26-2008, 4:40 PM
What do you have in your tank, and what are your water parameters?

08-26-2008, 5:09 PM
dont forget shale. has a "less compact" look to it compated to slate


08-26-2008, 5:20 PM
Granite and slate are probably your best choices.

08-26-2008, 6:09 PM
Basically all Igneous and most Metamorphic rock are safe to use. Very few types of Sedimentary rocks can be used.

08-26-2008, 6:14 PM
Obsidian is also safe, but be sure there are no sharp edges that could wound the fish. You can file any edges down, but it can be a lengthy process. Be VERY wary of any stones that have powdery green or yellow composition to them (copper and sulfur respectively). The exception here are the agates as these rocks are totally matrixed.

08-26-2008, 6:25 PM
ok thx guys