Hello. i have a simple question.

I have about 100LBS of rock in my back yard, these rocks have been there for over 6 month and are dry and white no algae or anything on them, I took them out when I redecorated my tank with fake coral and sculptures.
Now I want to put them back into the tank.

If I use these rocks again, can something bad happen to my tank and damage the water levels?

Thanks for your help...