Dark brown dry rock

[Emery]

Has anyone ever ran across a dark brown dry rock? I recently got a bunch of rock from a local reefer and threw it in a rubber maid for a bleach bath. After the bleach bath I took it all out and found this one piece that is a very dark brown. Is this even reef rock? I don't want to put it in my tank if it's not reef safe.

 

[BlueCursor]

If the other rock in the pic was bleached too, I don't think your bleach was strong enough. Chip away part of the dark brown rock to see if it is only the surface or that is the rock color. I would also re-soak in stronger bleach solution.

 

[Emery]

A piece broke off the brown rock and its that color all the way thru. I was planning on running another bleach bath because the rocks weren't 100% white yet. So I'm hoping another few days in a stronger solution will do the trick. I need to start curing this stuff to get the build rolling.

 

[Flippers4pups]

If your not sure, don't use it. It's most likely not calcium carbonate based and possibly has some form of metal/elements in it.

 

[BlueCursor]

If it's that color all the way through, I would ditch that rock. It's probably a land rock that got mixed in and not limestone. Not worth the risk. It could easily leach something into the tank water over time and cause you issues. The fact that it has tons of worms on it makes me think it has lots of iron and/or phosphate in it.

 

[ludnix]

The dark rocks look like lace rock. You can use a dab of acidic solution like vinegar to test the rocks. The calcium based rocks will fizz with vinegar as they react. The lace rock will might fizz at first until the surface is clean but should not after that.