Why is my return pump making bubbles?

[pfoster40]

I just did a water change on my tank, and I put plenty of water back into my sump. When I cut my return pump back its sending a mess load of bubbles into my tank. During my water change I had to cut off my skimmer and my return pump. Does anyone have an answer for me? Please help guys.

 

[chris4869]

It sounds like your pump is starving of water. Where did you put the valve? Is it on the input side of the pump or the output side?

 

[125G Reefer]

PVC or rubber line?? Rubber line will sometimes get the squeez, and get an air pocket going. Only one way to relieve it, remove line and reconnect tightly.