slate

So my newly built slate decor is ready to go in the tank, but I have to remove the old rocks to get them to fit right. Should I leave some of the old stuff in to keep my cycle from crashing?

Ok bare with me here I know this is a strange one but my local nature Reserve has two large lakes , can’t fish them as it’s protected , obviously Being from Good old Lizzies England They are cold water fish , carp roach perch pike etc but there is an abundance of slate and wood just in the water...

i found alot of this rock in my garden which im guessing is slate but not sure and it had patches of black stuff on it which i think is tar i have sterilised the rock/slate and scraped as much of the black stuff of as possible i have put it in my tank but i have no fish in the tank yet and am...