Are these rocks aquarium safe? Anyone know?
 

Hey guys I picked up some rock fragments from neighbor's that were getting their yards done. They had extra fragments. Anyone know what type of rock it is and if it is safe? I really hope its safe! It's really beautiful I think. :/

I'm not a rock expert, but they look like a form of slate. Slate would be ok in an aquarium. You should put some in a bucket of water and measure the pH, let it sit for 24 hours and measure the pH again...

Well thanks for the reply. :) I will do that unless someone knows FOR sure. :) Still may do that anyways.

You don't know what it has been treated with or exposed to. I would soak and water change it for a week minimum and water test it a few times. If you have a less prized tank you could test it in AFTER you've soaked, rinsed, tested (and repeated) that's be a good start.

It's just my fry tank at the moment.

If there is chemicals and I put it in the fish tank would I notice pretty soon with fish dying or would it slowly kill the fish ie mutate them? :/

I doubt you'd get ninja turtles or anything. IT would probably screw with your cycled tank's benny bacteria, and cause a spike and probable/possible fishie death.

I've never tried it myself, but I've heard that if you pour some white vinegar on it and it fizzes it's no good for an aquarium.

Hmmm, well I guess I'll have to hope not... I think they will look nice in the tank and maybe I'm incorrect feeling that they probably don't have chemicals, so the risk might be worth it. They are just some stone from making a wall/outdoor flooring....

I'll try the vinegar.

I also heard that nitrate (or possibly nitrite) test will fizzle if its bad (better than vinegar)... but if it is nitrate, then I can't use it. Can anyone confirm if it's nitrite or nitrate test?

I've only heard the vinegar trick also, found some rocks near my place, got vinegar, turns out they had a load of copper in them, thank god I checked first!

I hate to rain on your parade, but in those pictures it really looks like those rocks have some considerable rust buildup. Rust means iron and too much iron could be really problematic.

Then again, it could just be dirt and I'm seeing things.