925 gph pump trouble??

[Claudekim123]

hi guys, I'm new to the forum.. Anyways. I was wondering why my new pump does this?? When I plug it in, it spins well with no rattle or other sounds..but as soon as I put it in the water, it stops the motor completely and the impeller starts rattling and vibrating back and forth like there's something stuck in it... But when a little bit of air is stuck in the actual impeller housing, it starts up and pumps all the air out of the housing and stalls again.. When I have the pump i pellet partially submerged, it also starts pumping like crazy and so on.. In conclusion the pump doesn't work without air present.. Which is really weird.. Plz help

Ps. This is the pump Submersible Water Pump 220V FOR Aquarium Fish Tank Pond Rockery Fountain | eBay