Check for an air lock first.

That’s the most common fix when the pump runs but no water moves. Turn the pump off, open the air bleed valve on top of the filter, then crack the pump lid slightly to let trapped air out. Water should start flowing once air is gone.

If that doesn’t work, check the skimmer basket and pump basket for debris. A clogged basket or a stuck skimmer weir can choke off water flow even with the pump humming. Also make sure all suction-side valves are open — someone might have bumped them.

Worst case, the impeller is jammed with a small rock or piece of mulch. You’ll have to pull the pump housing apart to check. But try the easy stuff first. Nine times out of ten it’s air or a basket.

Don’t let the pump run dry for more than a minute or two. That’ll melt the seal fast.