Try to choose wood that is dried out or has been laying in a stream or pond. No fresh wood. The sap could be dangerous to fish. Stay away from Pine, Locust or other soft wood. Take your fingernail and push it into the wood. If your fingernail makes a dent then don't use it. You can use hard wood like Popular, oak, Walnut, Birch or something along those lines. Grapevine is also okay. When you get it home, scrub it down and boil it for awhile. Or soak it in a bucket of water for a week changing the water daily. This will help get rid of any bad stuff it may have soaked up.
For rocks. Take along some vinegar. When you find a rock you like make a scratch in it and pour on some vinegar. If it fizzes it has lime in it and will raise you PH. I have heard it said that sandstone is not good for a tank but I have used it and never had a problem. Just make sure it doesn't fall apart in water. Good luck on you hunt.
