Wow thanks for all the help!
Here's what our smaller turtle looks like;
and here's the tank - sorry its not a clear pic - i don't have a camera, only phone camera
the uvb light above the tank is sitting on glass - so sounds like i need to remove the glass? and maybe get some extra lights?
There are big stones, fake plants (occassionally real ones too), gravel (too big to eat at the moment), part of a cuttlefish, drift wood and a fake log also in the tank.
the terrapins bask a lot on the turtle dock but don't like doing so when people are in the room very much. i guess this is normal?