Final answer:
The nurse can instruct the certified nursing assistant to check the level of the water seal on the chest tube.
Step-by-step explanation:
The nurse can instruct the certified nursing assistant to check the level of the water seal on the chest tube. The water seal is an important component of the chest tube system and indicates that there is proper functioning and no air leaks. The nurse should ensure that the water level remains at the prescribed level to maintain effective chest tube drainage.