Powersweep pumps?

[leslr]

Cheapreef
The pre-filter isn't for the impeller its for the little gear-wheel. The last couple of times it stuck before using the stuff, all that stopped it was a grain of sand in the teeth. Other than that its a great little water mover.
Also check the manufactured date on the pump. The old ones(last year) were subject to corrosion till they changed the materials
leslr.