Heres another way to look at that.
Every animal in the tank produces phosphates.If it takes a crap,its releasing organic phosphates.Every time we feed,we add organic phosphates.So a hares not going to make that much of a difference there.
If it was me,I'd do a big water change,scrub every rock in the old water with a stiff bristled brush and then add some lettuce nudis and a hare to keep the algae gone.