It’s a big job, but I’m working on cleaning out one of my old 45 gallons to set up again…We live in an area that close by there are large amounts of limestone… yep I know what that does to the water… in some of those areas there are a lot of fossils… for example, I have a 4 inch fossil of a snail shell… I’m assuming these would be about the same as adding a piece of limestone the size of the fossil… but also in this tank I had several pieces of petrified wood… not sure if that has the same composition, as a fossil from a chunk of limestone, I they are wood color, not the color of limestone, and I’m not positive where they came from… do you guys think they will leach anything into the water, the way limestone does???