Quote Originally Posted by AlgaeFarmer View Post
The pump has been priming then quickly (about 30 seconds) losing vacuum with the water level inside the trap dropping quickly. while this is happening the pump is loudly cavitating and struggling to prime itself. Then it finally catches up only to quickly develop another bubble and frustratingly drop out again only to repeat this again and again.
This is indicative of either a stuck weir in the skimmer or your water level is too low. While this is happening, look inside the skimmer and see if there is vortex forming and sucking in air.