How do I deter possums from one specific tree

Just want to say that I totally respect the right of possums to chill and set up their homes in trees in my backyard. However, there’s one tree that they seem to love which is very annoying because they are weeing and pooping in my pool. Is there a way to deter them from a specific tree, without killing them obviously. Would much prefer they set up shop in the next tree over (which is the same species).