For aquariums, the best "glue" to use is aquarium silicon. You can get it at the pet store. People use it to seal leaks in aquariums but you can use it for all sorts of things.
Best not to put wood in the water unless it's cork bark. Most wood has been treated with chemicals that will leach into the water. In addition, wood that hasn't been treated with rot if constantly wet.
You can make a very nice basking platform with cork bark. It has a rough texture and turtles like to climb on it. It holds up very well in water and it floats.
Also best not to put paint in the aquarium. Turtles will bite just about anything and would probably chip the paint off after time.


