along with this question, since it might help out your search since it takes many many years for actual driftwood to become waterlogged enough to sink i belive? what kind of screws can you use to screw your driftwood into a piece of slate or somoehting to hold it down? it obviously cant rust or leach
Any hardwood will work and it must be old dried wood. Fresh wood will still have the sap in it and that's what has the toxins. Stainless steel screws will work to fasten it to a base as long as there are no sharp edges exposed that would injure a fish. Aquarium safe epoxies will work also.
I found a nice log in South Florida just lying in the woods behind a workshop. No idea what type of wood, maybe Sea Grape or Gumbo Limbo, both common in the area. It was long dead, but floated, so it went into a 'kiddie pool' along with some other smaller pieces for several months until the tank was ready. It worked well, however, it really gave off a lot of tannins, the tank water was usually orange between water changes. It has since been moved into a bigger tank and has lasted several years. You might also want to test the wood in a tank with expendable fishes like feeders or guppies, just to be sure it's not toxic.
Just be sure that it is a hard wood and a well dried piece. But drift wood does a dream of softening and acidifying your tank water. so if you have almost any CA or SA fish they will be greatfull for the addition. Plus Pleco, ottos and other algae eating fish seem to love knawing at the wood.
well i made my own and all i did was boiled the wood for about 2 1/2 hrs just in case....left it in a bucket full of water and held them down under water with a heavy stone for about two weeks.....no success....the wood still floats......so i drilled under the pieces that kept floating ( of course where you cant see them ) and zip tied small stones to them....then when you go and put them in the tank, position them to an angle to where you cant see the zip ties.....or hide them....