Pellet diet, bright green stool and constant eating?

Well for one thing and all Pellet diet is not the best to have him on. He also needs some seeds and fruits, veggies and an pasta. I have a African Grey and he was raised on just pellets and he is a very skinny bird and has always remained so. Everyone thinks there is something wrong, he has been tested and is ok. I think the all Pellet diet was not the best for him. Maybe your bird feels he is just not getting everything he needs.