There is an Eureka can and an object is put on it.
- If the object is floating, then there is no weight difference for the water container. (
)
- If the object is fully submerged, then the water container is getting heavier since no more bouyancy force is equal to the weight of the object. (
). It will be
heavier than before.
- If the object floating in its own liqud, (e.g. ice in water) then if the solid part melts the liquid level does not change.
)
). It will be 
heavier than before.