Aqualifter question

[Stones]

Make sure the tube going into your sump is above the water level so that a siphon can not start. I'm assuming that the tube was submerged in your sump at a level higher than the level of the tube submerged in your top off pail. If it isn't possible to have the tube going into your sump above the water level, drill a small hole in the tubing above the water level to act as a siphon break.