can you put concrete in tank?

[chrisalmand]

I dug up a really neat looking piece of concrete and was wondering if it would be safe to put in my tank,post rinsing

 

[OnoIgotICH]

You have to stable the PH of the rock to the aquarium.

get some water and put the rock in it.

Test the water for PH. That is the PH of the rock.
Over a 30 day period, raise the rock of the PH

 

[demonsp]

Rinse it off real good , then leave in the sun for a few days or boil it then rinse. It should be fine but not sure if i would want to use myself. GL