You & Sue A. seem to be on the same wavelength about this... yes, it can
easily go back to the turtle pond, it's about 30 feet away. I don't know
how well their orientation works, but he could just go there by hearing
(splashing from filter return etc...). But he's still in the bigger pond
for 2 weeks now.

Turtles don't take hints very well, he'll probably come back. And if he
doesn't
find what he needs in the one pond he'll probably head back to the other
pond.