osmolator dosen't always pump

[coraladdict]

My Tunze osmolator dosen't always pump,I could here it but nothing comes out this has happened the first time I started it and then today.I have to fiddle with it taking in and out of the water.This osmolator is three weeks old.
Thanks

 

[rvitko]

Tip the pump up to let the air out, this is the usual cause, air in the pump.

 

[coraladdict]

THANKS