Hello My red eared slider is currently carrying an egg... could I add a section in her basking tank for nesting? The egg will not fertilize as she's never mated.
You can, but they usually don't work well. Best options are outdoor. Indoor nesting boxes would be the next best option and those don't really work well either. An in-tank setup are usually pretty messy and it's hard to know if the turtle would except it.
They are very instinctive about nesting. Her eggs might not be fertilized but she wants to do her best to lay them properly. If it’s warm enough where you are, you might be able to make an outing of it.