Are you shure it is tape worm? If you pulled it and it came out Im more in the side of a nematod of some kind. What does it look like? If its a white worm like thing its defenetly a nematod, a tape worm its really flat and has segments wich easily break. By the way if the turt looks healty and eats you dont have anything to worry about, in fact unless your turt was langishing it is probably more dangerous to try to deworm him due to the toxicity of the medication. After all its all to natural for turts to have parasites and snappers are no push over. If it looks fine just give it lots of food and space, you may not have to do anything. By the side note the presence of parasites its one of the reasons why it is preferable to buy cb reptiles insted of catching them yourself, cb normal comon snappers are readbly avaible and cheap, just make shure you have that REALLY big tank or pond ready for it.