Yesterday I finished closing our pool. Depressing......I want summer back!

This past season was an unusual one in terms of my DE filter's lack of pressure rise over the season. Because my filter is oversized, it's not unusual to go all season on a single charge. But normally pressure will rise 5lbs or more during the season. This season, pressure only rose 1-2lbs!

I thought perhaps there might be problem with the filter (we've had it since the pool was installed in March 2004), but the water remained crystal clear all season and there was no evidence of DE getting inti the pool. Perhaps we just had an unusually "clean" year?

Any thoughts?