I found a really good, big piece of wood in Kaikoura a while back while fishing. Naturally i brought it home for my tank. It sat around for some time as i was away in Oz working, i'm now home. I had set my tank up and thought the piece of wood would just sink to the bottom when added, how wrong i was.
So i tied weights to it and that worked but it wouldn't sit how i wanted it and the weights looked ugly. So i took it out and have had it soaking in a large drum for the last month, thinking this would work. Once again i tried it in the tank and it still floated, very annoying. I came up with a great idea one night and have just completed the mission.
I first set the piece of wood up in the empty tank to find the very bottom and balance points. I then drilled a series of holes, mainly at the ends and some in the middle, about the diameter of a 20 cent coin and varying depths. I went down to the local tyre store and got a whole lot of their spent wheel weights, lead of course. I melted them in a couple of pots, do this outside as it stinks to the high heavens. I then poured the hot melted lead into the drilled holes.
Hey presto one piece of wood sitting in the bottom of the tank, no ugly weights tied to it. I thought this may help others having trouble with wood not sinking. It would work with any size piece of wood just change the drill bit size etc.