Hi Rob,

Could the water be coming from another return jet or maybe being siphoned from the main drain/skimmer? Whenever I clean my pump basket I have to close the main drain and crack open the return line (open air bleed) to keep water from siphoning above water level and back down and backwards through my filter (my pump basket is below water level). Perhaps something like that is happening to you. Try taking the pump basket cover off and see if the flows stops.