Originally Posted by falconboy99
One way to know if the rocks are safe enough:
1.Use the rocks that you are confident with so that if you rub them on a fifty dollar blue ray disk, it won't get scratched.
2. Rub them on a fifty dollar blue ray disk. If the disk gets scratched, then its not safe.
FYI:The blue ray disk is incentive to try hard to pick out the one that even might scratch the Betta even a little bit.
SO, then rocks ARE safe if chosen carefully for smoothness?
Also, I was told by someone that the way you know a rock (it's source: limestone, lava, ect) is safe for aquarium use is to pour vinegar over it. If it bubbles, it is not safe; no bubbles, then the rock is a compatible material. Has anyone heard this?