water pump not priming UPDATED PROBLEM FIXED

Some set-ups introduce a filter at the exit of the fresh water tank at the point that water feeds the plumbing to the water pump. This filter sometimes gets clogged with a fine film that establishes itself within the tank over the years. This film is not harmful but somtimes floats rather than staying attached to the sides of the fresh water tank. When you drain the tank at the end of the season, tiny portions of this film will settle on the bottom of the tank then refloat back when refilling the tank. But eventually it WILL find it's way to that filter and cause the symtom you describe. SOLUTION... disconnect the outlet plumbing going to the water pump. Remove the fitting on the water tank that the plumbing to the water pump connects. When removing the fitting there will probably be the filter I described as part of the fitting and most likely will have some of that white film I described earlier, wrapped around the filter. That film is restricting the water flow and the pump will churn up air bubbles as it tries to prime the system. This film WILL build up even with regular draining and desinfecting every season at start-up.