yeo its actually better to use to cycle a tank.
Just set up a bucket of salt water to wash off the rocks first before adding to the tank the dieoff can really stink up the house.
and other thing depending on where you get your rock from and where in the world it came from there can be some bad things liek mantis and crabs that arent good to have. you can get a bucket of a higher slainity water and dip for just a couple of mintues and most of the time it will drive them out of the rocks. just research what hitchikers come from what part of the world
Mike