i3dm what you said is so true. Because of the deep nose, it is hard to make it removable. Afterwards, I develop a method to make it removable. First, I put all the lead balls into the sandwich plastic bag and lower it to the nose. Put the plane nose down and stick a wood stick into weight puddle.
The plane still flies good with my current cg. I just need to relocate my batteries but I am so lazy doing that. Next time, when I need to replace the batteries then I'll relocate it.