Okay I went to my local creek and just to start off I got a small peice of wood that was in the water and I broke it into two. How long should I boil it? How long til it starts to sink? I just started boiling it about 15-20 min. and I want to know when do I know when its done and ready to be put into my tank? And how do you know if the wood you get is safe for your aquarium(if you look for wood by a creek/river) before taking it?