I have changed the support for the filament rol.
Wooden frame with spindels under the printer.
PVA compartiment is "closed"
On top a cardboard box.
The front closed with a plastic hanging door.
This works very well!
To determine the remaining filament on the coil. Length is an indication between an under and above value. Depending on the number of turns of the filament at a certain distance from the outside of the coil.