Ive got some kiln dried wood that I will be using in my fish tank, but want it saturated so it sinks.

Its been in a big tank (weighted down to the bottom) for a few weeks now, and although the buoyancy has reduced loads, it still does float slowly.

I had it in my tank before and had a big rock on it. Does warmer water aid in penetrating the wood?

Any ideas would be good!