Is it okay to add local rocks from my garden to the tank for the fish to hide in and around? If so, how would I make sure it is clean and not going to contaminate the tank? Right now I have a 46G bowfront with 35lbs of natural pebbles substrate, 3 fake plants, one real plant, 3 zebra danio, & 5 cardinal tetra. The tank is about 2 1/2 wks old. I am back into the hobby after a 9 year break to raise 4 children, 9,6,4,&2.