I like to by root wood, like Mopani, it sinks right away so there's no need to use weights. The look is different than driftwood though. The first pieces I bought were not Mopani, they were still from South Africa and they did not leach any tannins. I cannot remember the name but will post when I find out. Due to civil unrest there it is almost impossible to no find. I then bought two pieces of Mopani. The first spans the entire length of my tank and did not leach any tannins. The second was another story and I boiled in may times until you could not see the water and then put it in the tank. The tannins started the next day, but the tannins are good for the tank and the fish and they go away. The bootom line, IMO, is that root wood is the way to go, if you search there are some pretty cool pieces out there and no weighing down. Boil it and the amount of time for tannins to expire is shortened considerably. With the root wood it is also easier to fit the pieces together to create cool labyrinths in your tank, IMO.