CO2 Diffuser question

I have a pressurized CO2 system, the diffuser is a glass bell that is
usually 1/3 filled with water other 2/3 are the gas which is diffusing into
the water thought a kind of a hard membrane - which worked very well. for
some reasons the water are no longer in the bell which also means I cannot
see the CO2 bubble count. could the CO2 pushed out the water I think it
did.... does this indicates any problem ?
10x


gizmo