I bought a piece of driftwood from my lfs last week and am having the worst time keping it down. I let it soak for 4 days and tried putting it in the tank. It just won't stay down no matter what. It is attached to a square of slate yet the substrate isn't holding it down....still torpedoing towards the top.Are there any anchoring techniques to use? Should I remove it from the tank for more soaking? And if that's the case, is there anything I can do to chill the buoyance out quicker? So far I've done nothing but let it soak in a large container of water. It's too big to boil but should I have used scalding water?