It is submersible and it has been used several years in the past. Thanks for any help you can provide.

I would remove the hose from the pump to the waterfalls and turn on to see if it still shuts down. Does it pump any water over the falls? When you say “shuts off” it completely stops running? Or, hums but doesn’t push water?

It is pumping over the falls for the 5 minutes and then stops running all together.

Sorry, that is strange. I think I would be buying a new pump. There's something else going on besides the impeller I'm guessing. You did say this one had been used for "several years".

Yes it is old just wasn't sure if it was a part that could be fixed, I see so many videos etc saying don't just pitch your pump try this or that (Impeller bearings etc) but no clue what the symptoms of each item would be to know what to try.

Here’s what’s stumping me: a pump doesn’t have an off/on switch. You plug it in and it runs. If the impeller was broken, the pump would run but wouldn’t push water. If the impeller was jammed the motor would burn out. If there was an electrical “leak” the gfi would trip. None of these things are happening.

And my husband says that at first it is "pushing" the water and then it goes to "pulling" the water then shuts off and this exact same cycle has repeated itself like 18 or more times even clocked it a few times and it is 5 minutes each time. We cleaned everything out in all areas and when pump comes out there is no debris. I too am stumped (which is not hard when it comes to mechanical things)

I don't know much about pumps, but maybe it's just overheating? Do you have it connected to a GFCI? I suppose that would trip if it were overheating. The fact that it seems to suck water in, right before it quits might be because the propeller stops for some reason? Sorry, I'm not of much help. I think it's time for a new pump......but don't throw the old one out until you're sure the new one works.

I have never set up a pondless system, but I would think that a plausable answer is that the tank volume is too small and runs out of water and perhaps begins to draw back on the outflow. I would certainly take the pump to a place where you can watch it run.

Chas, that was my thought also. Maybe the issue is with the water returning to reservoir too slowly and not enough water to pump in the reservoir.

TY! Wold the tank volume change though because it has been the same since it was built in 2008 and worked fine so if I had the wrong size pump for the reservoir wouldn't I know it by now?

Knowing that the system worked before Does make my low volume theory less likely but not impossible. Perhaps your water vault volume has been decreased by crudding up with years of junk. In any case, if you can get the pump out, I think you should put it in a bath tub or something and watch it run.

BTW, mag drive pumps don't get damaged by a stopped impeller. I don't know about regular pumps. Probably not the issue anyway.

TY