@noromance,
I connect the tank drain to some hose that travels to filter "1 then another length of hose to filter #2, then another length of hose to the RV pump, then a long length of hose that I manually hold inside the tank when the pump is running.
I connect the tank drain to some hose that travels to filter "1 then another length of hose to filter #2, then another length of hose to the RV pump, then a long length of hose that I manually hold inside the tank when the pump is running.