My boyfriend started a small saltwater tank in an old 20-gal I had lying around. I know nothing about saltwater, but we are learning together. He just set it up 2 days ago, and he has live rock, live sand, and a couple of damsels. Can I help him speed up the cycling process by putting in some gravel from my freshwater aquarium, or will the salt kill that bacteria? I wasn't sure if it's the same bacteria needed or not. Thanks!