I found like a cement piece of rock, u could say, and I was wondering if it would be ok to add it to my aquarium if I boiled it kill the bacterial?
jimk said:Some rocks dissolve and will change your water chemistry. They may release metals or other impurities into your tank. I'm not sure where you would find it, but if you put muriatic acid on the rock and the rock starts to bubble, then you probably should not use it. Rocks like slate and granite are usually fine if well washed.

rottbo said:cement prob not, real rock though will work if you clean and boil the hell out of it
jimk said:Some rocks dissolve and will change your water chemistry. They may release metals or other impurities into your tank. I'm not sure where you would find it, but if you put muriatic acid on the rock and the rock starts to bubble, then you probably should not use it. Rocks like slate and granite are usually fine if well washed.