I shut off the main pump and breakers to the main and booster pumps. Replaced the cartridge filters with the clean spares, reassembled the filter unit and started the main pump. All fine. However, not my Polaris 280 is dead in the water, It has been working fine since April and it strikes me as too much of a coincidence that it is dead after I shut off the pumps and cleaned the filters.
Did I lose prime in the booster, how can I tell if it is working right? I did not initially close the suction and other normally open valves after shutting off the main pump, not even sure I need to do that when cleaning the filters.