the white stuff could be "white fly"., U ~9 t1 E+ A$ o1 S% n8 _
I had the same problem before. It because your plant is too wet. I showed the leaves twice a day for a whole week, then the white filies were all gone.5 B$ T- ]! ?4 J$ X- D& w0 S
Hibiscus is a typical plant, show helps a lot.