2 Clogged pre-filter. If you have a cartridge or vu-flow filter ahead of your Bubble Up, clean or change it, it may be fouled with iron or sediments. Then put the system back on line and see last paragraph. If you have a backwashing filter, it may have become blocked with a burst of sediment, initiate a manual Backwash in attempt to restore flow. If successful proceed to last paragraph. If flow is not restored call Reliable Radon, LLC.