Please, please don't tap him on the nose. Dogs' noses are extremely sensitive and it would actually encourage his aggressive behavior. It is very unlikely for him to associate the tap with his biting. Dogs don't think like us.
As another poster said, when he bites give him time out and competely ignore him no matter what he does. Put him in another room, or his x-pen if you have one. Give him treats when he plays nice. He will try to please you. Dogs bite each other when they are playing. My 3 month old pup bites my nose when she gets too excited too (especially if I am lying on the floor when playing). He should grow out of it though. Try to have some patience, and I am sure things will work out.
Best of luck!!!
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