200 Level

203 - Chapter 3

Protecting Mag Drives

These little pumps are almost maintenance-free. They are hard to overheat as long as they are kept submerged, and can run for years without failure -- IF they are kept clean. Two things will kill them; one can be repaired, one can’t. The first situation is pretty common – a small piece of mulch or twig gets past the prefilter and jams the impeller. When the flow stops, most folks’ first impulse is to unplug and re-plug the pump, to free the impeller, but this can backfire and snap the ceramic shaft that the impeller spins on. Luckily, the shaft, impeller and magnet assembly can usually be replaced at a modest cost.


Tip #2 - When flow stops, unplug the pump, check for blockage and make sure the impeller can spin freely BEFORE plugging the pump back in. Use a pencil or screwdriver to rotate the impeller one full turn. If it doesn’t turn freely, remove the impeller housing, find the debris and remove it. This goes for all pumps.

The second situation that’s especially damaging to Mag Drives is to have the pump sitting directly in the pond, down in silt or sediment. Constantly pumping abrasive grit can wear the bushings that the impeller shaft rides in. Once worn, the shaft will start to wobble and the Mag will start to fail. Usually, the bushings are difficult or impossible to replace, so that’s it for the pump.

Tip #3 - Either mount the pump in a skimmer, or keep any pump that’s sitting in a pond a few inches off the bottom, on a flat stone, to keep abrasive sand out of the pump.