Buckets heavier than others

A few of my plants are a lot heavier than other ones even after they drain out...even smaller plants are heavier than big ones. is this anything to worry about? could it be a salt build up?

no...its just the moisture content in the soil...smaller plants uptake water slower than larger plants with larger root structures. this is why a smaller plant in a bucket the same size as a larger plant weighs more

sweet thanks...i was hoping it wasn't a draining problem